[fixes #2838] Handle anonymous classes properly

Generated qualified names (e.g. Outer.Inner) now stop at anonymous
classes instead of adding an empty part. All handlers that add static
fields/methods/types now add error messages instead of generating
invalid code.

test/transform/resource/after-ecj/DataInAnonymousClass.java

@@ -0,0 +1,50 @@
+import lombok.Data;
+public class DataInAnonymousClass {
+  Object annonymous = new Object() {
+    @Data class Inner {
+      private String string;
+      public @java.lang.SuppressWarnings("all") String getString() {
+        return this.string;
+      }
+      public @java.lang.SuppressWarnings("all") void setString(final String string) {
+        this.string = string;
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") boolean equals(final java.lang.Object o) {
+        if ((o == this))
+            return true;
+        if ((! (o instanceof Inner)))
+            return false;
+        final Inner other = (Inner) o;
+        if ((! other.canEqual((java.lang.Object) this)))
+            return false;
+        final java.lang.Object this$string = this.getString();
+        final java.lang.Object other$string = other.getString();
+        if (((this$string == null) ? (other$string != null) : (! this$string.equals(other$string))))
+            return false;
+        return true;
+      }
+      protected @java.lang.SuppressWarnings("all") boolean canEqual(final java.lang.Object other) {
+        return (other instanceof Inner);
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") int hashCode() {
+        final int PRIME = 59;
+        int result = 1;
+        final java.lang.Object $string = this.getString();
+        result = ((result * PRIME) + (($string == null) ? 43 : $string.hashCode()));
+        return result;
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+        return (("Inner(string=" + this.getString()) + ")");
+      }
+      public @java.lang.SuppressWarnings("all") Inner() {
+        super();
+      }
+    }
+    x() {
+      super();
+    }
+  };
+  public DataInAnonymousClass() {
+    super();
+  }
+}