[javac] fix quickfix to implement inherited abstract methods

- add mapping for error id for missing abstract method implementations
- fixed an NPE that would prevent the error from being shown on
  anonymous classes
- fix binding logic for anonymous classes

example to try out: use the quickfix to add a stub implementation of
method() to the anonymous class:

```java
public class Parent {

  static interface IMethodable {
    void method();
  }

  public static void myMethod() {
    IMethodable methodable = new IMethodable() {
    };
    methodable.method();
  }

}
```

Future work: fix the diagnostic range on anonymous classes. We might
need access to the AST, since we ideally want to highlight `IMethodable`
from the constructor invocation.

Signed-off-by: David Thompson <[email protected]>

org.eclipse.jdt.core.javac/src/org/eclipse/jdt/core/dom/JavacBindingResolver.java

@@ -180,6 +180,16 @@ ITypeBinding resolveType(EnumDeclaration enumDecl) {
 		return null;
 	}
 
+	@Override
+	ITypeBinding resolveType(AnonymousClassDeclaration anonymousClassDecl) {
+		resolve();
+		JCTree javacNode = this.converter.domToJavac.get(anonymousClassDecl);
+		if (javacNode instanceof JCClassDecl jcClassDecl) {
+			return new JavacTypeBinding(jcClassDecl.type, this);
+		}
+		return null;
+	}
+
 	public IBinding getBinding(final Symbol owner, final com.sun.tools.javac.code.Type type) {
 		if (owner instanceof final PackageSymbol other) {
 			return new JavacPackageBinding(other, this);

org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/JavacProblemConverter.java

@@ -105,7 +105,7 @@ private static org.eclipse.jface.text.Position getDiagnosticPosition(JCDiagnosti
 
 	private static org.eclipse.jface.text.Position getDiagnosticPosition(String name, int startPosition, JCDiagnostic jcDiagnostic)
 			throws IOException {
-		if (name != null) {
+		if (name != null && !name.isEmpty()) {
 			DiagnosticSource source = jcDiagnostic.getDiagnosticSource();
 			JavaFileObject fileObject = source.getFile();
 			CharSequence charContent = fileObject.getCharContent(true);
@@ -149,6 +149,7 @@ public static int toProblemId(Diagnostic<? extends JavaFileObject> javacDiagnost
 			case "compiler.err.cant.apply.symbols" -> IProblem.UndefinedConstructor;
 			case "compiler.err.premature.eof" -> IProblem.ParsingErrorUnexpectedEOF; // syntax error
 			case "compiler.err.report.access" -> convertNotVisibleAccess(javacDiagnostic);
+			case "compiler.err.does.not.override.abstract" -> IProblem.AbstractMethodMustBeImplemented;
 			case COMPILER_WARN_MISSING_SVUID -> IProblem.MissingSerialVersion;
 			case COMPILER_WARN_NON_SERIALIZABLE_INSTANCE_FIELD -> 99999999; // JDT doesn't have this diagnostic
 			// TODO complete mapping list; dig in https://github.com/openjdk/jdk/blob/master/src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties