[groovy] fix GrDocInlinedTagImpl#getContainingComment

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/psi/impl/GrDocInlinedTagImpl.java

@@ -1,10 +1,10 @@
 // Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
-
 package org.jetbrains.plugins.groovy.lang.groovydoc.psi.impl;
 
 import com.intellij.lang.ASTNode;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.tree.TokenSet;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtilCore;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NonNls;
@@ -58,7 +58,7 @@ public class GrDocInlinedTagImpl extends GroovyDocPsiElementImpl implements GrDo
 
   @Override
   public GrDocComment getContainingComment() {
-    return (GrDocComment)getParent();
+    return PsiTreeUtil.getParentOfType(this, GrDocComment.class);
   }
 
   @Override