Report diagnostic on import with explicit import class if class was imported earlier.

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/resolve/resolutionApi.kt

@@ -82,7 +82,7 @@ public fun ResolutionFacade.resolveImportReference(
     val importDirective = JetPsiFactory(project).createImportDirective(ImportPath(fqName, false))
     val qualifiedExpressionResolver = this.getFrontendService(moduleDescriptor, QualifiedExpressionResolver::class.java)
     return qualifiedExpressionResolver.processImportReference(
-            importDirective, moduleDescriptor, BindingTraceContext(), packageFragmentForVisibilityCheck = null).getAllDescriptors()
+            importDirective, moduleDescriptor, BindingTraceContext(), packageFragmentForVisibilityCheck = null)?.getAllDescriptors() ?: emptyList()
 }
 
 //NOTE: idea default API returns module search scope for file under module but not in source or production source (for example, test data )

idea/testData/quickfix/conflictingImports/removeDuplicateImport.kt

@@ -0,0 +1,5 @@
+// "Remove conflicting import for 'java.util.ArrayList'" "true"
+package test
+
+import java.util.ArrayList
+import java.util.ArrayList<caret>

idea/testData/quickfix/conflictingImports/removeDuplicateImport.kt.after

@@ -0,0 +1,4 @@
+// "Remove conflicting import for 'java.util.ArrayList'" "true"
+package test
+
+import java.util.ArrayList

idea/testData/quickfix/conflictingImports/removeDuplicateImportWithAlias.kt

@@ -0,0 +1,5 @@
+// "Remove conflicting import for 'java.util.ArrayList'" "true"
+package test
+
+import java.util.ArrayList as foo
+import java.util.ArrayList as foo<caret>

idea/testData/quickfix/conflictingImports/removeDuplicateImportWithAlias.kt.after

@@ -0,0 +1,4 @@
+// "Remove conflicting import for 'java.util.ArrayList'" "true"
+package test
+
+import java.util.ArrayList as foo

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -723,6 +723,18 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
             String fileName = JetTestUtils.navigationMetadata("idea/testData/quickfix/conflictingImports/removeConflictingImport.kt");
             doTest(fileName);
         }
+
+        @TestMetadata("removeDuplicateImport.kt")
+        public void testRemoveDuplicateImport() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/quickfix/conflictingImports/removeDuplicateImport.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("removeDuplicateImportWithAlias.kt")
+        public void testRemoveDuplicateImportWithAlias() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/quickfix/conflictingImports/removeDuplicateImportWithAlias.kt");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("idea/testData/quickfix/createFromUsage")