Make toString usage more clear

.gitignore

@@ -5,4 +5,6 @@ build
 out
 *.class
 *.iml
+*.ipr
+*.iws
 .DS_Store

build.gradle

@@ -4,8 +4,16 @@ plugins {
 }
 
 allprojects {
+    apply plugin: 'idea'
+
     group = 'com.widen.oss'
     ext.repo = 'https://github.com/Widen/tabitha'
+
+    idea.module.iml {
+        beforeMerged { module ->
+            module.dependencies.clear()
+        }
+    }
 }
 
 subprojects {

tabitha-core/src/main/java/com/widen/tabitha/Variant.java

@@ -130,6 +130,17 @@ public Optional<Double> getFloat() {
         return Optional.empty();
     }
 
+    /**
+     * Return a string representation of this variant value.
+     *
+     * All variant types can be converted to their appropriate string representation using this method. The string
+     * equivalent will maintain as much precision as possible and is suitable for writing a variant value to a text-only
+     * format, such as a CSV.
+     *
+     * @return String equivalent of this value.
+     */
+    public abstract java.lang.String toString();
+
     // Private to prevent extending with unbounded variant types.
     private Variant() {
     }

tabitha-delimited/src/main/java/com/widen/tabitha/plugins/delimited/DelimitedRowWriter.java

@@ -28,7 +28,7 @@ public DelimitedRowWriter(OutputStream outputStream, DelimitedFormat format) {
     public void write(List<Variant> cells) {
         String[] cols = cells
             .stream()
-            .map(Object::toString)
+            .map(Variant::toString)
             .map(String.class::cast)
             .toArray(String[]::new);