Add JavaDoc to both new extensions

#433

junit-jupiter-migration-support/src/main/java/org/junit/jupiter/migrationsupport/rules/ExternalResourceSupport.java

@@ -14,13 +14,36 @@
 
 import java.util.function.Function;
 
+import org.junit.Rule;
 import org.junit.jupiter.api.extension.AfterEachCallback;
 import org.junit.jupiter.api.extension.BeforeEachCallback;
 import org.junit.jupiter.api.extension.TestExtensionContext;
 import org.junit.jupiter.migrationsupport.rules.adapter.AbstractTestRuleAdapter;
 import org.junit.jupiter.migrationsupport.rules.adapter.ExternalResourceAdapter;
 import org.junit.jupiter.migrationsupport.rules.member.RuleAnnotatedMember;
 import org.junit.platform.commons.meta.API;
+import org.junit.rules.TestRule;
+import org.junit.rules.Verifier;
+
+/**
+ * This {@code Extension} provides native support for subclasses of
+ * the {@code Verifier} rule from JUnit 4.
+ * {@code Rule}-annotated fields as well as methods are supported.
+ *
+ * <p>By using this class-level extension on a test class such
+ * {@code Verifier} implementations in legacy code bases
+ * can be left unchanged including the JUnit 4 rule import statements.
+ *
+ * <p>However, if you intend to develop a <em>new</em> extension for
+ * JUnit 5 please use the new extension model of JUnit Jupiter instead
+ * of the rule-based model of JUnit 4.
+ *
+ *
+ * @since 5.0
+ * @see Verifier
+ * @see TestRule
+ * @see Rule
+ */
 
 @API(Experimental)
 public class ExternalResourceSupport implements BeforeEachCallback, AfterEachCallback {

junit-jupiter-migration-support/src/main/java/org/junit/jupiter/migrationsupport/rules/VerifierSupport.java

@@ -14,13 +14,35 @@
 
 import java.util.function.Function;
 
+import org.junit.Rule;
 import org.junit.jupiter.api.extension.AfterEachCallback;
 import org.junit.jupiter.api.extension.TestExtensionContext;
 import org.junit.jupiter.migrationsupport.rules.adapter.AbstractTestRuleAdapter;
 import org.junit.jupiter.migrationsupport.rules.adapter.VerifierAdapter;
 import org.junit.jupiter.migrationsupport.rules.member.RuleAnnotatedMember;
 import org.junit.platform.commons.meta.API;
+import org.junit.rules.ExternalResource;
+import org.junit.rules.TestRule;
 
+/**
+ * This {@code Extension} provides native support for subclasses of
+ * the {@code ExternalResource} rule from JUnit 4.
+ * {@code Rule}-annotated fields as well as methods are supported.
+
+ * <p>By using this class-level extension on a test class such
+ * {@code ExternalResource} implementations in legacy code bases
+ * can be left unchanged including the JUnit 4 rule import statements.
+ *
+ * <p>However, if you intend to develop a <em>new</em> extension for
+ * JUnit 5 please use the new extension model of JUnit Jupiter instead
+ * of the rule-based model of JUnit 4.
+ *
+ *
+ * @since 5.0
+ * @see ExternalResource
+ * @see TestRule
+ * @see Rule
+ */
 @API(Experimental)
 public class VerifierSupport implements AfterEachCallback {