java completion: use context substitutor even for methods whose type parameters can be inferred from parameter types (IDEA-148623)

java/java-impl/src/com/intellij/codeInsight/completion/JavaCompletionContributor.java

@@ -390,7 +390,7 @@ public class JavaCompletionContributor extends CompletionContributor {
                         return type.isAssignableFrom(returned);
                       }
                     });
-                    if (matchingExpectation != null && SmartCompletionDecorator.hasUnboundTypeParams(method, matchingExpectation)) {
+                    if (matchingExpectation != null) {
                       call.setInferenceSubstitutor(SmartCompletionDecorator.calculateMethodReturnTypeSubstitutor(method, matchingExpectation), position);
                     }
                   }

java/java-tests/testData/codeInsight/completion/normalSorting/PreferCollectionsStaticOfExpectedType.java

@@ -0,0 +1,9 @@
+import java.util.*;
+
+public class MainClass1 {
+
+  List<String> foo(){
+    return Collections.un<caret>
+  }
+}
+

java/java-tests/testSrc/com/intellij/codeInsight/completion/NormalCompletionOrderingTest.groovy

@@ -713,4 +713,8 @@ interface TxANotAnno {}
     checkPreferredItems 0, 'xzMap', 'xaString'
   }
 
+  public void testPreferCollectionsStaticOfExpectedType() {
+    checkPreferredItems 0, 'unmodifiableList', 'unmodifiableCollection'
+  }
+
 }