`UastStringLiteralReferenceProvider` as a replacement for `UastLiteralReferenceProvider`

plugins/java-i18n/src/com/intellij/codeInspection/i18n/JavaI18nUtil.java

@@ -60,7 +60,7 @@ public class JavaI18nUtil extends I18nUtil {
     return isPassedToAnnotatedParam(expression, AnnotationUtil.PROPERTY_KEY, resourceBundleRef, null);
   }
 
-  public static boolean mustBePropertyKey(@NotNull ULiteralExpression expression, @Nullable Ref<? super UExpression> resourceBundleRef) {
+  public static boolean mustBePropertyKey(@NotNull UExpression expression, @Nullable Ref<? super UExpression> resourceBundleRef) {
     final UElement parent = expression.getUastParent();
     if (parent instanceof UVariable) {
       UAnnotation annotation = ((UVariable)parent).findAnnotation(AnnotationUtil.PROPERTY_KEY);

plugins/java-i18n/src/com/intellij/lang/properties/UastPropertiesReferenceProvider.java

@@ -7,7 +7,7 @@ import com.intellij.openapi.util.Ref;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiLanguageInjectionHost;
 import com.intellij.psi.PsiReference;
-import com.intellij.psi.UastLiteralReferenceProvider;
+import com.intellij.psi.UastStringLiteralReferenceProvider;
 import com.intellij.util.ProcessingContext;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.uast.*;
@@ -15,7 +15,7 @@ import org.jetbrains.uast.*;
 /**
  * @author cdr
  */
-class UastPropertiesReferenceProvider extends UastLiteralReferenceProvider {
+class UastPropertiesReferenceProvider extends UastStringLiteralReferenceProvider {
 
   private final boolean myDefaultSoft;
 

uast/uast-common/src/com/intellij/psi/UastInjectionHostReferenceProvider.kt

@@ -39,4 +39,27 @@ abstract class UastLiteralReferenceProvider : UastReferenceProvider() {
                                        host: PsiLanguageInjectionHost,
                                        context: ProcessingContext): Array<PsiReference>
 
+}
+
+abstract class UastStringLiteralReferenceProvider : UastReferenceProvider() {
+
+  override val supportedUElementTypes: List<Class<out UElement>> = listOf(UExpression::class.java)
+
+  override fun getReferencesByElement(element: UElement, context: ProcessingContext): Array<PsiReference> {
+    val injectionHost = context[REQUESTED_PSI_ELEMENT] as? PsiLanguageInjectionHost ?: return PsiReference.EMPTY_ARRAY
+    if (element is ULiteralExpression)
+      return getReferencesByULiteral(element, injectionHost, context) // simple string (java usually)
+    if (element is UPolyadicExpression) { // Kotlin, see KT-27283
+      return element.operands.asSequence().filterIsInstance<ULiteralExpression>().flatMap {
+        getReferencesByULiteral(it, injectionHost, context).asSequence()
+      }.toList().toTypedArray()
+    }
+
+    return PsiReference.EMPTY_ARRAY
+  }
+
+  abstract fun getReferencesByULiteral(uLiteral: ULiteralExpression,
+                                       host: PsiLanguageInjectionHost,
+                                       context: ProcessingContext): Array<PsiReference>
+
 }
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