ChangeMethodInvocationReturnType should shorten FQCN (#521)

Author: timtebeek

src/main/java/org/openrewrite/java/migrate/ChangeMethodInvocationReturnType.java

@@ -41,7 +41,7 @@ public class ChangeMethodInvocationReturnType extends Recipe {
     String methodPattern;
 
     @Option(displayName = "New method invocation return type",
-            description = "The return return type of method invocation.",
+            description = "The fully qualified new return type of method invocation.",
             example = "long")
     String newReturnType;
 
@@ -96,7 +96,7 @@ public J.VariableDeclarations visitVariableDeclarations(J.VariableDeclarations m
                                     mv.getTypeExpression().getPrefix(),
                                     Markers.EMPTY,
                                     emptyList(),
-                                    newReturnType,
+                                    newReturnType.substring(newReturnType.lastIndexOf('.') + 1),
                                     newType,
                                     null
                             )

src/test/java/org/openrewrite/java/migrate/ChangeMethodInvocationReturnTypeTest.java

@@ -17,6 +17,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.openrewrite.DocumentExample;
+import org.openrewrite.java.JavaParser;
 import org.openrewrite.test.RecipeSpec;
 import org.openrewrite.test.RewriteTest;
 
@@ -79,4 +80,46 @@ void bar() {
           )
         );
     }
+
+    @Test
+    void replaceVariableAssignmentFullyQualified() {
+        rewriteRun(
+          spec -> spec.recipe(new ChangeMethodInvocationReturnType("bar.Bar bar()", "java.math.BigInteger"))
+            .parser(JavaParser.fromJavaVersion()
+              //language=java
+              .dependsOn(
+                """
+                  package bar;
+                  public class Bar {
+                      public static Integer bar() {
+                          return null;
+                      }
+                  }
+                  """
+              )
+            ),
+          //language=java
+          java(
+            """
+              import bar.Bar;
+              class Foo {
+                  void foo() {
+                      Integer one = Bar.bar();
+                  }
+              }
+              """,
+            """
+              import bar.Bar;
+
+              import java.math.BigInteger;
+
+              class Foo {
+                  void foo() {
+                      BigInteger one = Bar.bar();
+                  }
+              }
+              """
+          )
+        );
+    }
 }