diff --git a/src/main/java/nl/stil4m/mollie/Client.java b/src/main/java/nl/stil4m/mollie/Client.java
index 541862e..3cb30ee 100644
--- a/src/main/java/nl/stil4m/mollie/Client.java
+++ b/src/main/java/nl/stil4m/mollie/Client.java
@@ -37,7 +37,7 @@ public Issuers issuers() {
     }
 
     public Refunds refunds(String paymentId) {
-        return dynamicClient.refunds(apiKey,paymentId);
+        return dynamicClient.refunds(apiKey, paymentId);
     }
 
     public Customers customers() {
@@ -47,7 +47,7 @@ public Customers customers() {
     public CustomerPayments customerPayments(String customerId) {
         return dynamicClient.customerPayments(apiKey, customerId);
     }
-    
+
     public Mandates mandates(String customerId) {
         return dynamicClient.mandates(apiKey, customerId);
     }
diff --git a/src/main/java/nl/stil4m/mollie/DynamicClient.java b/src/main/java/nl/stil4m/mollie/DynamicClient.java
index 6a9cd8c..4282bb6 100644
--- a/src/main/java/nl/stil4m/mollie/DynamicClient.java
+++ b/src/main/java/nl/stil4m/mollie/DynamicClient.java
@@ -46,7 +46,7 @@ public Customers customers(String apiKey) {
     public CustomerPayments customerPayments(String apiKey, String customerId) {
         return new CustomerPayments(apiKey, endpoint, requestExecutor, customerId);
     }
-    
+
     public Mandates mandates(String apiKey, String customerId) {
         return new Mandates(apiKey, endpoint, requestExecutor, customerId);
     }
diff --git a/src/main/java/nl/stil4m/mollie/ResponseOrError.java b/src/main/java/nl/stil4m/mollie/ResponseOrError.java
index 0abea6f..08dba6c 100644
--- a/src/main/java/nl/stil4m/mollie/ResponseOrError.java
+++ b/src/main/java/nl/stil4m/mollie/ResponseOrError.java
@@ -10,6 +10,13 @@ public class ResponseOrError<V> {
     private final Map error;
     private final Boolean success;
 
+    private ResponseOrError(int status, V data, Map error, Boolean success) {
+        this.status = status;
+        this.data = data;
+        this.error = error;
+        this.success = success;
+    }
+
     public static <V, T> ResponseOrError withError(int status, Map error) {
         return new ResponseOrError<>(status, null, error, false);
     }
@@ -18,13 +25,6 @@ public static <V, T> ResponseOrError withData(int status, V data) {
         return new ResponseOrError<>(status, data, null, true);
     }
 
-    private ResponseOrError(int status, V data, Map error, Boolean success) {
-        this.status = status;
-        this.data = data;
-        this.error = error;
-        this.success = success;
-    }
-
     public void get(Consumer<V> onSuccess, Consumer<Map> onError) {
         if (success) {
             onSuccess.accept(data);
diff --git a/src/main/java/nl/stil4m/mollie/concepts/AbstractConcept.java b/src/main/java/nl/stil4m/mollie/concepts/AbstractConcept.java
index a01b33e..48e7c6d 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/AbstractConcept.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/AbstractConcept.java
@@ -1,6 +1,15 @@
 package nl.stil4m.mollie.concepts;
 
-import static java.util.Objects.requireNonNull;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.type.TypeReference;
+import nl.stil4m.mollie.RequestExecutor;
+import nl.stil4m.mollie.ResponseOrError;
+import nl.stil4m.mollie.domain.Page;
+import org.apache.http.HttpEntity;
+import org.apache.http.client.methods.HttpUriRequest;
+import org.apache.http.entity.ContentType;
+import org.apache.http.entity.StringEntity;
+
 import java.io.IOException;
 import java.nio.charset.UnsupportedCharsetException;
 import java.util.Arrays;
@@ -8,70 +17,61 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-import org.apache.http.HttpEntity;
-import org.apache.http.client.methods.HttpUriRequest;
-import org.apache.http.entity.ContentType;
-import org.apache.http.entity.StringEntity;
-
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.core.type.TypeReference;
-
-import nl.stil4m.mollie.RequestExecutor;
-import nl.stil4m.mollie.ResponseOrError;
-import nl.stil4m.mollie.domain.Page;
+import static java.util.Objects.requireNonNull;
 
 public abstract class AbstractConcept<T extends Object> implements Concept<T> {
     private static final Collector<CharSequence, ?, String> URL_JOINER = Collectors.joining("/");
-    private static final TypeReference<Void> VOID_TYPE_REFERENCE = new TypeReference<Void>(){};
-    
+    private static final TypeReference<Void> VOID_TYPE_REFERENCE = new TypeReference<Void>() {
+    };
+
     private final TypeReference<Page<T>> pageTypeReference;
     private final TypeReference<T> singleTypeReference;
     private final String apiKey;
     private final String endpoint;
     private final RequestExecutor requestExecutor;
 
-    protected AbstractConcept(String apiKey, RequestExecutor requestExecutor,TypeReference<T> singleTypeReference,TypeReference<Page<T>> pageTypeReference, String... endPoint) {
+    protected AbstractConcept(String apiKey, RequestExecutor requestExecutor, TypeReference<T> singleTypeReference, TypeReference<Page<T>> pageTypeReference, String... endPoint) {
         this.apiKey = apiKey;
-        this.endpoint = requireNonNull(joinUrl(endPoint),"endPoint cannot be null or empty");
+        this.endpoint = requireNonNull(joinUrl(endPoint), "endPoint cannot be null or empty");
         this.requestExecutor = requestExecutor;
         this.singleTypeReference = singleTypeReference;
         this.pageTypeReference = pageTypeReference;
     }
-    
+
     private static String joinUrl(String... elements) {
         return trimToNull(Stream.of(elements)
                 .map(AbstractConcept::trimToNull)
-                .map(s->requireNonNull(s,"URL cannot contain null or blank elements: "+Arrays.asList(elements)))
+                .map(s -> requireNonNull(s, "URL cannot contain null or blank elements: " + Arrays.asList(elements)))
                 .collect(URL_JOINER));
     }
-    
+
     private static String trimToNull(String value) {
-        return value!=null && !value.trim().isEmpty()?value.trim():null;
+        return value != null && !value.trim().isEmpty() ? value.trim() : null;
     }
-    
+
     @Override
     public String url(String... elements) {
-        if(elements==null || elements.length==0) {
+        if (elements == null || elements.length == 0) {
             return this.endpoint;
         }
-        return joinUrl(this.endpoint,joinUrl(elements));
+        return joinUrl(this.endpoint, joinUrl(elements));
     }
-    
+
     @Override
     public ResponseOrError<Page<T>> requestPage(HttpUriRequest httpRequest) throws IOException {
         return requestExecutor.execute(apiKey, httpRequest, pageTypeReference);
     }
-    
+
     @Override
     public ResponseOrError<T> requestSingle(HttpUriRequest httpRequest) throws IOException {
         return requestExecutor.execute(apiKey, httpRequest, singleTypeReference);
     }
-    
+
     @Override
     public ResponseOrError<Void> requestVoid(HttpUriRequest httpRequest) throws IOException {
         return requestExecutor.execute(apiKey, httpRequest, VOID_TYPE_REFERENCE);
     }
-    
+
     @Override
     public HttpEntity buildHttpEntity(Object value) throws UnsupportedCharsetException, JsonProcessingException {
         return new StringEntity(requestExecutor.serialize(value), ContentType.APPLICATION_JSON);
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Concept.java b/src/main/java/nl/stil4m/mollie/concepts/Concept.java
index 019b78c..0f6edff 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Concept.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Concept.java
@@ -1,24 +1,22 @@
 package nl.stil4m.mollie.concepts;
 
-import java.io.IOException;
-import java.nio.charset.UnsupportedCharsetException;
-
-import org.apache.http.HttpEntity;
-import org.apache.http.client.methods.HttpUriRequest;
-
 import com.fasterxml.jackson.core.JsonProcessingException;
-
 import nl.stil4m.mollie.ResponseOrError;
 import nl.stil4m.mollie.domain.Page;
+import org.apache.http.HttpEntity;
+import org.apache.http.client.methods.HttpUriRequest;
+
+import java.io.IOException;
+import java.nio.charset.UnsupportedCharsetException;
 
 public interface Concept<T extends Object> {
     String url(String... elements);
-    
+
     ResponseOrError<Page<T>> requestPage(HttpUriRequest get) throws IOException;
-    
+
     ResponseOrError<T> requestSingle(HttpUriRequest get) throws IOException;
-    
+
     ResponseOrError<Void> requestVoid(HttpUriRequest get) throws IOException;
-    
+
     HttpEntity buildHttpEntity(Object value) throws UnsupportedCharsetException, JsonProcessingException;
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Create.java b/src/main/java/nl/stil4m/mollie/concepts/Create.java
index 269dab6..a574cac 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Create.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Create.java
@@ -1,13 +1,12 @@
 package nl.stil4m.mollie.concepts;
 
-import java.io.IOException;
-
+import nl.stil4m.mollie.ResponseOrError;
 import org.apache.http.client.methods.HttpPost;
 
-import nl.stil4m.mollie.ResponseOrError;
+import java.io.IOException;
+
+public interface Create<R extends Object, O extends Object> extends Concept<R> {
 
-public interface Create<R extends Object,O extends Object> extends Concept<R> {
-    
     default ResponseOrError<R> create(O create) throws IOException {
         HttpPost httpPost = new HttpPost(url());
         httpPost.setEntity(buildHttpEntity(create));
diff --git a/src/main/java/nl/stil4m/mollie/concepts/CustomerPayments.java b/src/main/java/nl/stil4m/mollie/concepts/CustomerPayments.java
index 481bd24..21ad4ff 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/CustomerPayments.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/CustomerPayments.java
@@ -4,9 +4,9 @@
 import nl.stil4m.mollie.domain.CustomerPayment;
 import nl.stil4m.mollie.domain.Payment;
 
-public class CustomerPayments extends AbstractConcept<Payment> implements ListAll<Payment>,Create<Payment,CustomerPayment> {
-    
+public class CustomerPayments extends AbstractConcept<Payment> implements ListAll<Payment>, Create<Payment, CustomerPayment> {
+
     public CustomerPayments(String apiKey, String endpoint, RequestExecutor requestExecutor, String customerId) {
-        super(apiKey,requestExecutor,Payments.SINGLE_TYPE,Payments.PAGE_TYPE,endpoint,"customers",customerId,"payments");
+        super(apiKey, requestExecutor, Payments.SINGLE_TYPE, Payments.PAGE_TYPE, endpoint, "customers", customerId, "payments");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Customers.java b/src/main/java/nl/stil4m/mollie/concepts/Customers.java
index 99d2b96..ff115e0 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Customers.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Customers.java
@@ -1,18 +1,19 @@
 package nl.stil4m.mollie.concepts;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-
 import nl.stil4m.mollie.RequestExecutor;
 import nl.stil4m.mollie.domain.CreateCustomer;
 import nl.stil4m.mollie.domain.Customer;
 import nl.stil4m.mollie.domain.Page;
 import nl.stil4m.mollie.domain.UpdateCustomer;
 
-public class Customers extends AbstractConcept<Customer> implements ListAll<Customer>,GetById<Customer>,Create<Customer,CreateCustomer>,Update<Customer,UpdateCustomer> {
-    private static final TypeReference<Page<Customer>> PAGE_TYPE = new TypeReference<Page<Customer>>() {};
-    private static final TypeReference<Customer> SINGLE_TYPE = new TypeReference<Customer>() {};
+public class Customers extends AbstractConcept<Customer> implements ListAll<Customer>, GetById<Customer>, Create<Customer, CreateCustomer>, Update<Customer, UpdateCustomer> {
+    private static final TypeReference<Page<Customer>> PAGE_TYPE = new TypeReference<Page<Customer>>() {
+    };
+    private static final TypeReference<Customer> SINGLE_TYPE = new TypeReference<Customer>() {
+    };
 
     public Customers(String apiKey, String endpoint, RequestExecutor requestExecutor) {
-        super(apiKey,requestExecutor,SINGLE_TYPE,PAGE_TYPE,endpoint,"customers");
+        super(apiKey, requestExecutor, SINGLE_TYPE, PAGE_TYPE, endpoint, "customers");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Delete.java b/src/main/java/nl/stil4m/mollie/concepts/Delete.java
index 78f604a..9efb0a5 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Delete.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Delete.java
@@ -1,10 +1,9 @@
 package nl.stil4m.mollie.concepts;
 
-import java.io.IOException;
-
+import nl.stil4m.mollie.ResponseOrError;
 import org.apache.http.client.methods.HttpDelete;
 
-import nl.stil4m.mollie.ResponseOrError;
+import java.io.IOException;
 
 public interface Delete<T extends Object> extends Concept<T> {
 
diff --git a/src/main/java/nl/stil4m/mollie/concepts/GetById.java b/src/main/java/nl/stil4m/mollie/concepts/GetById.java
index f75e6ed..7e13796 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/GetById.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/GetById.java
@@ -1,13 +1,12 @@
 package nl.stil4m.mollie.concepts;
 
-import java.io.IOException;
-
+import nl.stil4m.mollie.ResponseOrError;
 import org.apache.http.client.methods.HttpGet;
 
-import nl.stil4m.mollie.ResponseOrError;
+import java.io.IOException;
 
 public interface GetById<T extends Object> extends Concept<T> {
-    
+
     default ResponseOrError<T> get(String id) throws IOException {
         HttpGet httpGet = new HttpGet(url(id));
         return requestSingle(httpGet);
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Issuers.java b/src/main/java/nl/stil4m/mollie/concepts/Issuers.java
index 013ca05..c4fa813 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Issuers.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Issuers.java
@@ -1,16 +1,17 @@
 package nl.stil4m.mollie.concepts;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-
 import nl.stil4m.mollie.RequestExecutor;
 import nl.stil4m.mollie.domain.Issuer;
 import nl.stil4m.mollie.domain.Page;
 
-public class Issuers extends AbstractConcept<Issuer> implements ListAll<Issuer>,GetById<Issuer> {
-    private static final TypeReference<Page<Issuer>> PAGE_TYPE = new TypeReference<Page<Issuer>>() {};
-    private static final TypeReference<Issuer> SINGLE_TYPE = new TypeReference<Issuer>() {};
-    
+public class Issuers extends AbstractConcept<Issuer> implements ListAll<Issuer>, GetById<Issuer> {
+    private static final TypeReference<Page<Issuer>> PAGE_TYPE = new TypeReference<Page<Issuer>>() {
+    };
+    private static final TypeReference<Issuer> SINGLE_TYPE = new TypeReference<Issuer>() {
+    };
+
     public Issuers(String apiKey, String endpoint, RequestExecutor requestExecutor) {
-        super(apiKey,requestExecutor,SINGLE_TYPE,PAGE_TYPE,endpoint,"issuers");
+        super(apiKey, requestExecutor, SINGLE_TYPE, PAGE_TYPE, endpoint, "issuers");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/ListAll.java b/src/main/java/nl/stil4m/mollie/concepts/ListAll.java
index b74db4c..1ffa140 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/ListAll.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/ListAll.java
@@ -1,20 +1,19 @@
 package nl.stil4m.mollie.concepts;
 
-import java.io.IOException;
-import java.net.URISyntaxException;
-import java.util.Optional;
-
-import org.apache.http.client.methods.HttpGet;
-import org.apache.http.client.utils.URIBuilder;
-
 import nl.stil4m.mollie.ResponseOrError;
 import nl.stil4m.mollie.domain.Page;
 import nl.stil4m.mollie.domain.Payment;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.utils.URIBuilder;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.util.Optional;
 
 public interface ListAll<T extends Object> extends Concept<T> {
-    
+
     default ResponseOrError<Page<T>> all(Optional<Integer> count, Optional<Integer> offset) throws IOException, URISyntaxException {
-        return list(count,offset);
+        return list(count, offset);
     }
 
     default ResponseOrError<Page<T>> list(Optional<Integer> count, Optional<Integer> offset) throws IOException, URISyntaxException {
@@ -25,7 +24,7 @@ default ResponseOrError<Page<T>> list(Optional<Integer> count, Optional<Integer>
         HttpGet httpGet = new HttpGet(builder.build());
         return requestPage(httpGet);
     }
-    
+
     default ResponseOrError<Page<T>> next(Page<Payment> page) throws IOException {
         if (!page.getLinks().getNext().isPresent()) {
             throw new IllegalArgumentException("Page does not have next");
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Mandates.java b/src/main/java/nl/stil4m/mollie/concepts/Mandates.java
index 0c54df8..df0aa56 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Mandates.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Mandates.java
@@ -1,17 +1,18 @@
 package nl.stil4m.mollie.concepts;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-
 import nl.stil4m.mollie.RequestExecutor;
 import nl.stil4m.mollie.domain.CreateMandate;
 import nl.stil4m.mollie.domain.Mandate;
 import nl.stil4m.mollie.domain.Page;
 
-public class Mandates extends AbstractConcept<Mandate> implements ListAll<Mandate>,GetById<Mandate>,Create<Mandate,CreateMandate>,Delete<Mandate> {
-    private static final TypeReference<Page<Mandate>> PAGE_TYPE = new TypeReference<Page<Mandate>>() {};
-    private static final TypeReference<Mandate> SINGLE_TYPE = new TypeReference<Mandate>() {};
+public class Mandates extends AbstractConcept<Mandate> implements ListAll<Mandate>, GetById<Mandate>, Create<Mandate, CreateMandate>, Delete<Mandate> {
+    private static final TypeReference<Page<Mandate>> PAGE_TYPE = new TypeReference<Page<Mandate>>() {
+    };
+    private static final TypeReference<Mandate> SINGLE_TYPE = new TypeReference<Mandate>() {
+    };
 
     public Mandates(String apiKey, String endpoint, RequestExecutor requestExecutor, String customerId) {
-        super(apiKey,requestExecutor,SINGLE_TYPE,PAGE_TYPE,endpoint,"customers",customerId,"mandates");
+        super(apiKey, requestExecutor, SINGLE_TYPE, PAGE_TYPE, endpoint, "customers", customerId, "mandates");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Methods.java b/src/main/java/nl/stil4m/mollie/concepts/Methods.java
index 75315bf..c48a173 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Methods.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Methods.java
@@ -1,16 +1,17 @@
 package nl.stil4m.mollie.concepts;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-
 import nl.stil4m.mollie.RequestExecutor;
 import nl.stil4m.mollie.domain.Method;
 import nl.stil4m.mollie.domain.Page;
 
-public class Methods extends AbstractConcept<Method> implements ListAll<Method>,GetById<Method> {
-    private static final TypeReference<Page<Method>> PAGE_TYPE = new TypeReference<Page<Method>>() {};
-    private static final TypeReference<Method> SINGLE_TYPE = new TypeReference<Method>() {};
-    
+public class Methods extends AbstractConcept<Method> implements ListAll<Method>, GetById<Method> {
+    private static final TypeReference<Page<Method>> PAGE_TYPE = new TypeReference<Page<Method>>() {
+    };
+    private static final TypeReference<Method> SINGLE_TYPE = new TypeReference<Method>() {
+    };
+
     public Methods(String apiKey, String endpoint, RequestExecutor requestExecutor) {
-        super(apiKey,requestExecutor,SINGLE_TYPE,PAGE_TYPE,endpoint,"methods");
+        super(apiKey, requestExecutor, SINGLE_TYPE, PAGE_TYPE, endpoint, "methods");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Payments.java b/src/main/java/nl/stil4m/mollie/concepts/Payments.java
index 73924d1..28cb3c4 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Payments.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Payments.java
@@ -1,17 +1,18 @@
 package nl.stil4m.mollie.concepts;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-
 import nl.stil4m.mollie.RequestExecutor;
 import nl.stil4m.mollie.domain.CreatePayment;
 import nl.stil4m.mollie.domain.Page;
 import nl.stil4m.mollie.domain.Payment;
 
-public class Payments extends AbstractConcept<Payment> implements ListAll<Payment>,GetById<Payment>,Create<Payment,CreatePayment> {
-    protected static final TypeReference<Page<Payment>> PAGE_TYPE = new TypeReference<Page<Payment>>() {};
-    protected static final TypeReference<Payment> SINGLE_TYPE = new TypeReference<Payment>() {};
-    
+public class Payments extends AbstractConcept<Payment> implements ListAll<Payment>, GetById<Payment>, Create<Payment, CreatePayment> {
+    protected static final TypeReference<Page<Payment>> PAGE_TYPE = new TypeReference<Page<Payment>>() {
+    };
+    protected static final TypeReference<Payment> SINGLE_TYPE = new TypeReference<Payment>() {
+    };
+
     public Payments(String apiKey, String endpoint, RequestExecutor requestExecutor) {
-        super(apiKey,requestExecutor,SINGLE_TYPE,PAGE_TYPE,endpoint,"payments");
+        super(apiKey, requestExecutor, SINGLE_TYPE, PAGE_TYPE, endpoint, "payments");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Refunds.java b/src/main/java/nl/stil4m/mollie/concepts/Refunds.java
index b04996b..ea18cf6 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Refunds.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Refunds.java
@@ -1,17 +1,18 @@
 package nl.stil4m.mollie.concepts;
 
 import com.fasterxml.jackson.core.type.TypeReference;
-
 import nl.stil4m.mollie.RequestExecutor;
 import nl.stil4m.mollie.domain.CreateRefund;
 import nl.stil4m.mollie.domain.Page;
 import nl.stil4m.mollie.domain.Refund;
 
-public class Refunds extends AbstractConcept<Refund> implements ListAll<Refund>,GetById<Refund>,Create<Refund,CreateRefund>,Delete<Refund> {
-    private static final TypeReference<Page<Refund>> PAGE_TYPE = new TypeReference<Page<Refund>>() {};
-    private static final TypeReference<Refund> SINGLE_TYPE = new TypeReference<Refund>() {};
-    
+public class Refunds extends AbstractConcept<Refund> implements ListAll<Refund>, GetById<Refund>, Create<Refund, CreateRefund>, Delete<Refund> {
+    private static final TypeReference<Page<Refund>> PAGE_TYPE = new TypeReference<Page<Refund>>() {
+    };
+    private static final TypeReference<Refund> SINGLE_TYPE = new TypeReference<Refund>() {
+    };
+
     public Refunds(String apiKey, String endpoint, RequestExecutor requestExecutor, String paymentId) {
-        super(apiKey,requestExecutor,SINGLE_TYPE,PAGE_TYPE,endpoint,"payments",paymentId,"refunds");
+        super(apiKey, requestExecutor, SINGLE_TYPE, PAGE_TYPE, endpoint, "payments", paymentId, "refunds");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/nl/stil4m/mollie/concepts/Update.java b/src/main/java/nl/stil4m/mollie/concepts/Update.java
index 0104aa7..84e1362 100644
--- a/src/main/java/nl/stil4m/mollie/concepts/Update.java
+++ b/src/main/java/nl/stil4m/mollie/concepts/Update.java
@@ -1,13 +1,12 @@
 package nl.stil4m.mollie.concepts;
 
-import java.io.IOException;
-
+import nl.stil4m.mollie.ResponseOrError;
 import org.apache.http.client.methods.HttpPost;
 
-import nl.stil4m.mollie.ResponseOrError;
+import java.io.IOException;
+
+public interface Update<R extends Object, O extends Object> extends Concept<R> {
 
-public interface Update<R extends Object,O extends Object> extends Concept<R> {
-    
     default ResponseOrError<R> update(String id, O update) throws IOException {
         HttpPost httpPost = new HttpPost(url(id));
         httpPost.setEntity(buildHttpEntity(update));
diff --git a/src/main/java/nl/stil4m/mollie/domain/CreateMandate.java b/src/main/java/nl/stil4m/mollie/domain/CreateMandate.java
index 733a7ed..a043f51 100644
--- a/src/main/java/nl/stil4m/mollie/domain/CreateMandate.java
+++ b/src/main/java/nl/stil4m/mollie/domain/CreateMandate.java
@@ -1,10 +1,9 @@
 package nl.stil4m.mollie.domain;
 
-import java.util.Date;
-import java.util.Optional;
-
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Date;
+import java.util.Optional;
 
 public class CreateMandate {
     private final String method;
@@ -13,19 +12,19 @@ public class CreateMandate {
     private final Optional<String> consumerBic;
     private final Optional<Date> signatureDate;
     private final Optional<String> mandateReference;
-    
-    public CreateMandate(@Nonnull String method, 
-            @Nonnull String consumerName, 
-            @Nonnull String consumerAccount) {
-        this(method,consumerName,consumerAccount,null,null,null);
-    }
-    
-    public CreateMandate(@Nonnull String method, 
-            @Nonnull String consumerName, 
-            @Nonnull String consumerAccount, 
-            @Nullable String consumerBic, 
-            @Nullable Date signatureDate, 
-            @Nullable String mandateReference) {
+
+    public CreateMandate(@Nonnull String method,
+                         @Nonnull String consumerName,
+                         @Nonnull String consumerAccount) {
+        this(method, consumerName, consumerAccount, null, null, null);
+    }
+
+    public CreateMandate(@Nonnull String method,
+                         @Nonnull String consumerName,
+                         @Nonnull String consumerAccount,
+                         @Nullable String consumerBic,
+                         @Nullable Date signatureDate,
+                         @Nullable String mandateReference) {
         super();
         this.method = method;
         this.consumerName = consumerName;
diff --git a/src/main/java/nl/stil4m/mollie/domain/CreateRefund.java b/src/main/java/nl/stil4m/mollie/domain/CreateRefund.java
index f9cda7b..550af2f 100644
--- a/src/main/java/nl/stil4m/mollie/domain/CreateRefund.java
+++ b/src/main/java/nl/stil4m/mollie/domain/CreateRefund.java
@@ -1,8 +1,7 @@
 package nl.stil4m.mollie.domain;
 
-import java.util.Optional;
-
 import javax.annotation.Nullable;
+import java.util.Optional;
 
 public class CreateRefund {
     private final Optional<Double> amount;
diff --git a/src/main/java/nl/stil4m/mollie/domain/Mandate.java b/src/main/java/nl/stil4m/mollie/domain/Mandate.java
index 7b204be..bb204c5 100644
--- a/src/main/java/nl/stil4m/mollie/domain/Mandate.java
+++ b/src/main/java/nl/stil4m/mollie/domain/Mandate.java
@@ -1,33 +1,33 @@
 package nl.stil4m.mollie.domain;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
+
 import java.util.Date;
 import java.util.Map;
 import java.util.Optional;
 
-import com.fasterxml.jackson.annotation.JsonProperty;
-
 public class Mandate {
     private final String resource;
     private final String id;
     private final String status;
     private final String method;
     private final String customerId;
-    private final Map<String,Object> details;
+    private final Map<String, Object> details;
     private final Optional<String> mandateReference;
     private final Date createdDatetime;
 
     public Mandate(@JsonProperty("resource") String resource,
-                    @JsonProperty("id") String id,
-                    @JsonProperty("status") String status,
-                    @JsonProperty("method") String method,
-                    @JsonProperty("customerId") String customerId,
-                    @JsonProperty("details") Map<String, Object> details,
-                    @JsonProperty("mandateReference") Optional<String> mandateReference,
-                    @JsonProperty("createdDatetime") Date createdDatetime) {
+                   @JsonProperty("id") String id,
+                   @JsonProperty("status") String status,
+                   @JsonProperty("method") String method,
+                   @JsonProperty("customerId") String customerId,
+                   @JsonProperty("details") Map<String, Object> details,
+                   @JsonProperty("mandateReference") Optional<String> mandateReference,
+                   @JsonProperty("createdDatetime") Date createdDatetime) {
         this.resource = resource;
         this.id = id;
         this.status = status;
-        this.method= method;
+        this.method = method;
         this.customerId = customerId;
         this.details = details;
         this.mandateReference = mandateReference;
diff --git a/src/test/java/nl/stil4m/mollie/concepts/AbstractConceptTest.java b/src/test/java/nl/stil4m/mollie/concepts/AbstractConceptTest.java
index d3145ff..0ec178a 100644
--- a/src/test/java/nl/stil4m/mollie/concepts/AbstractConceptTest.java
+++ b/src/test/java/nl/stil4m/mollie/concepts/AbstractConceptTest.java
@@ -1,63 +1,63 @@
 package nl.stil4m.mollie.concepts;
 
-import static org.junit.Assert.*;
-
 import org.junit.Test;
 
+import static org.junit.Assert.assertEquals;
+
 public class AbstractConceptTest {
 
     @Test
     public void testConstructor() {
-        assertEquals("https://api.mollie.com/v1",new ConceptStub("https://api.mollie.com/v1").url());
-        assertEquals("https://api.mollie.com/v1/api",new ConceptStub("https://api.mollie.com/v1","api").url());
+        assertEquals("https://api.mollie.com/v1", new ConceptStub("https://api.mollie.com/v1").url());
+        assertEquals("https://api.mollie.com/v1/api", new ConceptStub("https://api.mollie.com/v1", "api").url());
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testConstructorNullUrl() {
-        new ConceptStub((String)null);
+        new ConceptStub((String) null);
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testConstructorNullArrayUrl() {
-        new ConceptStub((String[])null);
+        new ConceptStub((String[]) null);
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testConstructorEmptyUrl() {
         new ConceptStub("");
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testConstructorBlankUrl() {
         new ConceptStub(" ");
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testConstructorEmptyArray() {
         new ConceptStub(new String[]{});
     }
-    
+
     @Test
     public void testUrl() {
-        AbstractConcept<Boolean> sut = new ConceptStub("https://api.mollie.com/v1/api","customers");
-        assertEquals("https://api.mollie.com/v1/api/customers",sut.url());
-        assertEquals("https://api.mollie.com/v1/api/customers/someId",sut.url("someId"));
+        AbstractConcept<Boolean> sut = new ConceptStub("https://api.mollie.com/v1/api", "customers");
+        assertEquals("https://api.mollie.com/v1/api/customers", sut.url());
+        assertEquals("https://api.mollie.com/v1/api/customers/someId", sut.url("someId"));
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testUrlBlankElement() {
         new ConceptStub("https://api.mollie.com/v1").url(" ");
     }
-    
-    @Test(expected=NullPointerException.class)
+
+    @Test(expected = NullPointerException.class)
     public void testUrlNullElement() {
-        new ConceptStub("https://api.mollie.com/v1").url((String)null);
+        new ConceptStub("https://api.mollie.com/v1").url((String) null);
     }
-    
+
     private class ConceptStub extends AbstractConcept<Boolean> {
 
         protected ConceptStub(String... url) {
-            super(null, null,null,null,url);
+            super(null, null, null, null, url);
         }
     }
 }
\ No newline at end of file
diff --git a/src/test/java/nl/stil4m/mollie/concepts/MandatesIntegrationTest.java b/src/test/java/nl/stil4m/mollie/concepts/MandatesIntegrationTest.java
index 41a58e1..b7621d2 100644
--- a/src/test/java/nl/stil4m/mollie/concepts/MandatesIntegrationTest.java
+++ b/src/test/java/nl/stil4m/mollie/concepts/MandatesIntegrationTest.java
@@ -1,10 +1,14 @@
 package nl.stil4m.mollie.concepts;
 
-import static nl.stil4m.mollie.TestUtil.TEST_TIMEOUT;
-import static nl.stil4m.mollie.TestUtil.VALID_API_KEY;
-import static nl.stil4m.mollie.TestUtil.strictClientWithApiKey;
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.is;
+import nl.stil4m.mollie.Client;
+import nl.stil4m.mollie.ResponseOrError;
+import nl.stil4m.mollie.domain.CreateCustomer;
+import nl.stil4m.mollie.domain.CreateMandate;
+import nl.stil4m.mollie.domain.Customer;
+import nl.stil4m.mollie.domain.Mandate;
+import nl.stil4m.mollie.domain.Page;
+import org.junit.Before;
+import org.junit.Test;
 
 import java.io.IOException;
 import java.net.URISyntaxException;
@@ -13,16 +17,11 @@
 import java.util.Optional;
 import java.util.UUID;
 
-import org.junit.Before;
-import org.junit.Test;
-
-import nl.stil4m.mollie.Client;
-import nl.stil4m.mollie.ResponseOrError;
-import nl.stil4m.mollie.domain.CreateCustomer;
-import nl.stil4m.mollie.domain.CreateMandate;
-import nl.stil4m.mollie.domain.Customer;
-import nl.stil4m.mollie.domain.Mandate;
-import nl.stil4m.mollie.domain.Page;
+import static nl.stil4m.mollie.TestUtil.TEST_TIMEOUT;
+import static nl.stil4m.mollie.TestUtil.VALID_API_KEY;
+import static nl.stil4m.mollie.TestUtil.strictClientWithApiKey;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
 
 public class MandatesIntegrationTest {
 
@@ -32,35 +31,35 @@ public class MandatesIntegrationTest {
     public void before() throws InterruptedException, IOException {
         Thread.sleep(TEST_TIMEOUT);
         Client client = strictClientWithApiKey(VALID_API_KEY);
-        
+
         String uuid = UUID.randomUUID().toString();
         Map<String, Object> defaultMetadata = new HashMap<>();
         defaultMetadata.put("foo", "bar");
         defaultMetadata.put("id", uuid);
-        
+
         String name = "Test Customer " + uuid;
-        Customer customer = client.customers().create(new CreateCustomer(name, uuid+"@foobar.com", Optional.empty(), defaultMetadata)).getData();
-        
+        Customer customer = client.customers().create(new CreateCustomer(name, uuid + "@foobar.com", Optional.empty(), defaultMetadata)).getData();
+
         mandates = client.mandates(customer.getId());
     }
 
     @Test
     public void testList() throws IOException, URISyntaxException {
         ResponseOrError<Page<Mandate>> list = mandates.list(Optional.empty(), Optional.empty());
-        
+
         assertThat(list.getSuccess(), is(true));
     }
 
     @Test
     public void testCreate() throws IOException, URISyntaxException {
-    	// https://www.mollie.com/nl/docs/reference/mandates/create
-    	String method = "directdebit";
-    	String name = "Test geit";
-    	String account = "NL91ABNA0417164300";
-    	CreateMandate createMandate = new CreateMandate(method, name, account);
-    	
+        // https://www.mollie.com/nl/docs/reference/mandates/create
+        String method = "directdebit";
+        String name = "Test geit";
+        String account = "NL91ABNA0417164300";
+        CreateMandate createMandate = new CreateMandate(method, name, account);
+
         ResponseOrError<Mandate> result = mandates.create(createMandate);
-        
+
         // Mandates need to be enabled with your Mollie account (identifier with API key) in order to test this
         assertThat(result.getSuccess(), is(false));
         //assertThat(result.getData().getId(),notNullValue());
diff --git a/src/test/java/nl/stil4m/mollie/concepts/PaymentsIntegrationTest.java b/src/test/java/nl/stil4m/mollie/concepts/PaymentsIntegrationTest.java
index 92f231b..8082f10 100644
--- a/src/test/java/nl/stil4m/mollie/concepts/PaymentsIntegrationTest.java
+++ b/src/test/java/nl/stil4m/mollie/concepts/PaymentsIntegrationTest.java
@@ -68,7 +68,8 @@ public void testGetPayment() throws IOException, InterruptedException {
     public void testGetPaymentWithRefunds() throws IOException, InterruptedException {
         ResponseOrError<Payment> getResponse = payments.get("tr_3AdTKpQGii");
 
-        getResponse.get(payment -> assertThat(payment.getLinks().getRefunds().isPresent(), is(true)), errorData -> {});
+        getResponse.get(payment -> assertThat(payment.getLinks().getRefunds().isPresent(), is(true)), errorData -> {
+        });
 
     }
 
diff --git a/src/test/java/nl/stil4m/mollie/concepts/RefundsIntegrationTest.java b/src/test/java/nl/stil4m/mollie/concepts/RefundsIntegrationTest.java
index 80506be..23145db 100644
--- a/src/test/java/nl/stil4m/mollie/concepts/RefundsIntegrationTest.java
+++ b/src/test/java/nl/stil4m/mollie/concepts/RefundsIntegrationTest.java
@@ -1,28 +1,27 @@
 package nl.stil4m.mollie.concepts;
 
-import static nl.stil4m.mollie.TestUtil.TEST_TIMEOUT;
-import static nl.stil4m.mollie.TestUtil.VALID_API_KEY;
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.notNullValue;
-
-import java.io.IOException;
-import java.net.URISyntaxException;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-
-import org.junit.Before;
-import org.junit.Test;
-
 import nl.stil4m.mollie.Client;
 import nl.stil4m.mollie.ClientBuilder;
 import nl.stil4m.mollie.ResponseOrError;
 import nl.stil4m.mollie.domain.CreatePayment;
 import nl.stil4m.mollie.domain.CreateRefund;
-import nl.stil4m.mollie.domain.Payment;
 import nl.stil4m.mollie.domain.Page;
+import nl.stil4m.mollie.domain.Payment;
 import nl.stil4m.mollie.domain.Refund;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+import static nl.stil4m.mollie.TestUtil.TEST_TIMEOUT;
+import static nl.stil4m.mollie.TestUtil.VALID_API_KEY;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.notNullValue;
 
 public class RefundsIntegrationTest {
 
@@ -41,9 +40,9 @@ public void testGetRefunds() throws IOException, URISyntaxException, Interrupted
         ResponseOrError<Payment> payment = payments.create(new CreatePayment(Optional.empty(), 1.00, "Some description", "http://example.com", Optional.empty(), null));
         String id = payment.getData().getId();
         Refunds refunds = client.refunds(id);
-        
+
         ResponseOrError<Page<Refund>> all = refunds.all(Optional.empty(), Optional.empty());
-        
+
         assertThat(all.getSuccess(), is(true));
         Page<Refund> refundPage = all.getData();
         assertThat(refundPage.getCount(), is(0));
@@ -55,7 +54,7 @@ public void testGetRefunds() throws IOException, URISyntaxException, Interrupted
     public void testListRefundsForExistingPayment() throws IOException, URISyntaxException, InterruptedException {
         Payment payment = payments.create(new CreatePayment(Optional.empty(), 1.00, "Some description", "http://example.com", Optional.empty(), null)).getData();
         Refunds refunds = client.refunds(payment.getId());
-        
+
         ResponseOrError<Page<Refund>> all = refunds.all(Optional.empty(), Optional.empty());
 
         assertThat(all.getSuccess(), is(true));
@@ -72,9 +71,9 @@ public void testCancelNonExistingRefund() throws IOException {
         ResponseOrError<Payment> payment = payments.create(new CreatePayment(Optional.empty(), 1.00, "Some description", "http://example.com", Optional.empty(), null));
         assertThat(payment.getSuccess(), is(true));
         Refunds refunds = client.refunds(payment.getData().getId());
-        
+
         ResponseOrError<Void> cancel = refunds.delete("foo_bar");
-        
+
         assertThat(cancel.getSuccess(), is(false));
         assertThat(cancel.getError().get("error"), is(errorData));
     }
@@ -88,7 +87,7 @@ public void testGetNonExistingRefund() throws IOException {
         Refunds refunds = client.refunds(payment.getData().getId());
 
         ResponseOrError<Refund> get = refunds.get("foo_bar");
-        
+
         assertThat(get.getSuccess(), is(false));
         assertThat(get.getError().get("error"), is(errorData));
     }
@@ -100,10 +99,10 @@ public void testCreateRefund() throws IOException, URISyntaxException {
         errorData.put("message", "The payment is already refunded or has not been paid for yet");
         ResponseOrError<Payment> payment = payments.create(new CreatePayment(Optional.empty(), 1.00, "Some description", "http://example.com", Optional.empty(), null));
         Refunds refunds = client.refunds(payment.getData().getId());
-        
+
         CreateRefund createRefund = new CreateRefund(1.00);
         ResponseOrError<Refund> create = refunds.create(createRefund);
-        
+
         assertThat(create.getSuccess(), is(false));
         assertThat(create.getError().get("error"), is(errorData));
     }