[groovy] get rid of GrMultiSignature#EMPTY_SIGNATURE

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/api/signatures/GrMultiSignature.java

@@ -1,49 +1,7 @@
-/*
- * Copyright 2000-2014 JetBrains s.r.o.
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.
- */
+// 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.psi.api.signatures;
 
-import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiType;
-import org.jetbrains.annotations.NotNull;
-
-/**
- * @author Max Medvedev
- */
 public interface GrMultiSignature extends GrSignature {
+
   GrClosureSignature[] getAllSignatures();
-
-  GrMultiSignature EMPTY_SIGNATURE = new GrMultiSignature() {
-    @Override
-    public GrClosureSignature[] getAllSignatures() {
-      return GrClosureSignature.EMPTY_ARRAY;
-    }
-
-    @Override
-    public boolean isValid() {
-      return true;
-    }
-
-    @Override
-    public GrSignature curry(@NotNull PsiType[] args, int position, @NotNull PsiElement context) {
-      return this;
-    }
-
-    @Override
-    public void accept(@NotNull GrSignatureVisitor visitor) {
-      visitor.visitMultiSignature(this);
-    }
-  };
 }

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/impl/signatures/GrClosureSignatureUtil.java

@@ -278,7 +278,8 @@ public class GrClosureSignatureUtil {
     return ApplicabilityResult.applicable;
   }
 
-  static GrSignature curryImpl(GrClosureSignature original, PsiType[] args, int position, PsiElement context) {
+  @Nullable
+  static GrSignature curryImpl(@NotNull GrClosureSignature original, PsiType[] args, int position, @NotNull PsiElement context) {
     GrClosureParameter[] params = original.getParameters();
 
     List<GrClosureParameter> newParams = new ArrayList<>(params.length);
@@ -289,7 +290,7 @@ public class GrClosureSignatureUtil {
       position = params.length - args.length;
     }
 
-    if (position < 0 || position >= params.length) return GrMultiSignature.EMPTY_SIGNATURE;
+    if (position < 0 || position >= params.length) return null;
 
     for (int i = 0; i < params.length; i++) {
       if (params[i].isOptional()) {