Fix AddMissingMethodImplementation generating stubs for inherited methods

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

@@ -22,10 +22,13 @@
 import org.openrewrite.java.JavaTemplate;
 import org.openrewrite.java.MethodMatcher;
 import org.openrewrite.java.search.UsesType;
+import org.openrewrite.java.tree.Flag;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.JavaType;
 import org.openrewrite.java.tree.TypeUtils;
 
+import java.util.Iterator;
+
 import static org.openrewrite.java.tree.J.ClassDeclaration.Kind.Type.Interface;
 
 @EqualsAndHashCode(callSuper = false)
@@ -80,13 +83,15 @@ public J.ClassDeclaration visitClassDeclaration(J.ClassDeclaration cs, Execution
                     .anyMatch(methodDeclaration -> methodMatcher.matches(methodDeclaration, classDecl))) {
                 return classDecl;
             }
-            // If a superclass already provides the method, don't add it.
-            JavaType.FullyQualified supertype = classDecl.getType() != null ? classDecl.getType().getSupertype() : null;
-            while (supertype != null) {
-                if (supertype.getMethods().stream().anyMatch(methodMatcher::matches)) {
-                    return classDecl;
+            // If a concrete implementation is already available through inheritance, don't add it.
+            if (classDecl.getType() != null) {
+                Iterator<JavaType.Method> visibleMethods = classDecl.getType().getVisibleMethods();
+                while (visibleMethods.hasNext()) {
+                    JavaType.Method method = visibleMethods.next();
+                    if (!method.hasFlags(Flag.Abstract) && methodMatcher.matches(method)) {
+                        return classDecl;
+                    }
                 }
-                supertype = supertype.getSupertype();
             }
 
             return classDecl.withBody(JavaTemplate.apply( methodTemplateString, new Cursor( getCursor(), classDecl.getBody() ), classDecl.getBody().getCoordinates().lastStatement() ));

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

@@ -151,4 +151,24 @@ class SubClass extends SuperClass {}
         );
     }
 
+    @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/648")
+    @Test
+    void skipWhenIndirectSuperclassAlreadyHasMethod() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              interface I1 {}
+              class GrandSuperClass implements I1 {
+                  public void m1() {
+                      System.out.println("m1 from grandsuper");
+                  }
+              }
+              class SuperClass extends GrandSuperClass {}
+              class SubClass extends SuperClass {}
+              """
+          )
+        );
+    }
+
 }