Fix final field @InjectMock recipe (#679)

Author: nielsdebruin

src/main/java/org/openrewrite/java/testing/mockito/NoInitializationForInjectMock.java

@@ -36,7 +36,8 @@ public String getDisplayName() {
 
     @Override
     public String getDescription() {
-        return "Removes unnecessary initialization for fields annotated with `@InjectMocks` in Mockito tests.";
+        return "Removes unnecessary initialization for fields annotated with `@InjectMocks` in Mockito tests. If the" +
+               " field was final, the final modifier is removed.";
     }
 
     @Override
@@ -47,7 +48,10 @@ public J.VariableDeclarations visitVariableDeclarations(J.VariableDeclarations v
                 J.VariableDeclarations vd = super.visitVariableDeclarations(variableDeclarations, ctx);
 
                 if (isField(getCursor()) && new AnnotationService().matches(getCursor(), INJECT_MOCKS)) {
-                    return vd.withVariables(ListUtils.map(vd.getVariables(), it -> it.withInitializer(null)));
+                    return maybeAutoFormat(vd, vd
+                                    .withModifiers(ListUtils.map(vd.getModifiers(), modifier -> modifier.getType() == J.Modifier.Type.Final ? null : modifier))
+                                    .withVariables(ListUtils.map(vd.getVariables(), it -> it.withInitializer(null))),
+                            ctx, getCursor().getParentOrThrow());
                 }
 
                 return vd;

src/test/java/org/openrewrite/java/testing/mockito/NoInitializationForInjectMockTest.java

@@ -69,4 +69,40 @@ class MyTest {
           )
         );
     }
+
+    @Test
+    void removeInitializationOfInjectMocksWithFinal() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              class MyObject {
+                  private String someField;
+
+                  public MyObject(String someField) {
+                      this.someField = someField;
+                  }
+              }
+              """
+          ),
+          java(
+            """
+              import org.mockito.InjectMocks;
+
+              class MyTest {
+                  @InjectMocks
+                  final MyObject myObject = new MyObject("someField");
+              }
+              """,
+            """
+              import org.mockito.InjectMocks;
+
+              class MyTest {
+                  @InjectMocks
+                  MyObject myObject;
+              }
+              """
+          )
+        );
+    }
 }