Allow parsing nested Groovy annotations (#4549)

* Allow parsing nested Groovy annotations

See: #4055 (comment)

* Polish

rewrite-groovy/src/main/java/org/openrewrite/groovy/GroovyParserVisitor.java

@@ -1205,6 +1205,9 @@ public void visitConstantExpression(ConstantExpression expression) {
                         text = "";
                     }
                     jType = JavaType.Primitive.Null;
+                } else if (expression instanceof AnnotationConstantExpression) {
+                    classVisitor.visitAnnotation((AnnotationNode) value);
+                    return ((Expression) classVisitor.pollQueue()).withPrefix(fmt);
                 } else {
                     throw new IllegalStateException("Unexpected constant type " + type);
                 }

rewrite-groovy/src/test/java/org/openrewrite/groovy/tree/AnnotationTest.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2021 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.groovy.tree;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.Issue;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.groovy.Assertions.groovy;
+
+@SuppressWarnings({"GroovyUnusedAssignment", "GrUnnecessarySemicolon"})
+class AnnotationTest implements RewriteTest {
+
+    @Test
+    void simple() {
+        rewriteRun(
+          groovy(
+            """
+              @Foo
+              class Test {
+              }
+              """
+          )
+        );
+    }
+
+    @Issue("https://github.com/openrewrite/rewrite/issues/4055")
+    @Test
+    void nested() {
+        rewriteRun(
+          groovy(
+            """
+              @Foo(bar = @Bar)
+              class Test {
+              }
+              """
+          )
+        );
+    }
+}