Remove the dead JUnit 4 build configuration and stale references

The four junit:junit exclusions no longer exclude anything: wagon-provider-test
stopped declaring junit, and stripping all four leaves junit:junit absent from
every resolved tree. Do not restore them with the managed version.

Author: slachiewicz

pom.xml

@@ -189,11 +189,6 @@ under the License.
         <artifactId>wagon-ssh-common</artifactId>
         <version>${project.version}</version>
       </dependency>
-      <dependency>
-        <groupId>junit</groupId>
-        <artifactId>junit</artifactId>
-        <version>4.13.2</version>
-      </dependency>
       <dependency>
         <groupId>org.codehaus.plexus</groupId>
         <artifactId>plexus-testing</artifactId>
@@ -205,7 +200,7 @@ under the License.
         <version>1.5.1</version>
       </dependency>
       <!--
-       | The Plexus shim: org.eclipse.sisu.plexus supplies PlexusContainer and PlexusTestCase,
+       | The Plexus shim: org.eclipse.sisu.plexus supplies PlexusContainer,
        | and understands both META-INF/plexus/components.xml and JSR-330 @Named beans.
        | Its version is managed by maven-parent. Guice is "provided" in the sisu POM,
        | so it has to be declared here explicitly.

src/site/markdown/developer-guide.md

@@ -225,20 +225,21 @@ for the largest example of this in the project.
 
 `wagon-provider-test` contains abstract test cases that exercise a provider through
 the public API against a real endpoint that you set up. It is a `compile`-scope
-artifact that drags in JUnit 3-style `PlexusTestCase`, Mockito and Jetty; the
+artifact that drags in JUnit 5, `plexus-testing`, Mockito and Jetty; the
 `wagon-providers` parent POM already declares it at `test` scope for every provider
 module.
 
 ### `WagonTestCase`
 
-`WagonTestCase extends PlexusTestCase`. Two abstract methods:
+`WagonTestCase` is annotated `@PlexusTest` and implements `PlexusTestConfiguration`,
+which is what gives it a container. Two abstract methods:
 
 ```java
 protected abstract String getProtocol();          // the role hint, e.g. "file"
 protected abstract String getTestRepositoryUrl(); // where the tests should write
 ```
 
-`getWagon()` looks the provider up with `lookup(Wagon.ROLE, getProtocol())` and
+`getWagon()` looks the provider up with `container.lookup(Wagon.class, getProtocol())` and
 attaches an `observers.Debug` as both session and transfer listener, so a failing run
 prints a transcript.
 

wagon-providers/pom.xml

@@ -78,12 +78,6 @@ under the License.
       <groupId>org.apache.maven.wagon</groupId>
       <artifactId>wagon-provider-test</artifactId>
       <scope>test</scope>
-      <exclusions>
-        <exclusion>
-          <groupId>junit</groupId>
-          <artifactId>junit</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
   </dependencies>
 </project>

wagon-providers/wagon-http-lightweight/pom.xml

@@ -49,12 +49,6 @@ under the License.
       <artifactId>wagon-tck-http</artifactId>
       <version>${project.version}</version>
       <scope>test</scope>
-      <exclusions>
-        <exclusion>
-          <groupId>junit</groupId>
-          <artifactId>junit</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.codehaus.plexus</groupId>

wagon-providers/wagon-http/pom.xml

@@ -108,12 +108,6 @@ under the License.
       <artifactId>wagon-tck-http</artifactId>
       <version>${project.version}</version>
       <scope>test</scope>
-      <exclusions>
-        <exclusion>
-          <groupId>junit</groupId>
-          <artifactId>junit</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
 
   </dependencies>

wagon-providers/wagon-scm/pom.xml

@@ -48,7 +48,7 @@ under the License.
       <exclusions>
         <!--
          | Drags in plexus-container-default 1.0-alpha-9, which collides with the Plexus shim
-         | (two copies of PlexusContainer/PlexusTestCase on the test classpath).
+         | (two copies of PlexusContainer on the test classpath).
         -->
         <exclusion>
           <groupId>org.codehaus.plexus</groupId>

wagon-providers/wagon-ssh-common-test/pom.xml

@@ -60,12 +60,6 @@ under the License.
     <dependency>
       <groupId>org.apache.maven.wagon</groupId>
       <artifactId>wagon-provider-test</artifactId>
-      <exclusions>
-        <exclusion>
-          <groupId>junit</groupId>
-          <artifactId>junit</artifactId>
-        </exclusion>
-      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.apache.maven.wagon</groupId>

wagon-providers/wagon-ssh/src/test/java/org/apache/maven/wagon/providers/ssh/jsch/TestPrompter.java

@@ -28,7 +28,7 @@
  * {@code src/test/resources/META-INF/plexus/components.xml}.
  * <p>
  * {@code plexus-interactivity-api} stopped shipping a {@code META-INF/plexus/components.xml} in 1.3, so its
- * {@code DefaultPrompter} is invisible to the {@code plexus-container-default} that {@code PlexusTestCase} runs;
+ * {@code DefaultPrompter} is invisible to the {@code plexus-container-default} the tests run;
  * without a replacement every {@code lookup( Wagon.ROLE, "scp" )} fails because {@code ConsoleInteractiveUserInfo}
  * and {@code PrompterUIKeyboardInteractive} both require one.
  * <p>

wagon-providers/wagon-ssh/src/test/resources/META-INF/plexus/components.xml

@@ -22,7 +22,7 @@
   plexus-interactivity-api dropped its own META-INF/plexus/components.xml in 1.3 and only ships a sisu index, so
   plexus-container-default cannot see DefaultPrompter (which in any case now takes its collaborators through a
   constructor, which plexus-container-default cannot satisfy). Maven itself runs on sisu and is unaffected; only
-  the PlexusTestCase-based tests here need this descriptor.
+  the tests here need this descriptor.
 -->
 <component-set>
   <components>