Spring Support: Allow injection of SpEL into string literals with escape sequences

#KT-11904 Fixed

compiler/frontend/src/org/jetbrains/kotlin/psi/psiUtil/ktPsiUtil.kt

@@ -413,6 +413,7 @@ private val MODALITY_MODIFIERS = TokenSet.create(
 fun KtDeclaration.modalityModifier() = modifierFromTokenSet(MODALITY_MODIFIERS)
 
 fun KtStringTemplateExpression.isPlain() = entries.all { it is KtLiteralStringTemplateEntry }
+fun KtStringTemplateExpression.isPlainWithEscapes() = entries.all { it is KtLiteralStringTemplateEntry || it is KtEscapeStringTemplateEntry }
 
 val KtDeclaration.containingClassOrObject: KtClassOrObject?
         get() = (parent as? KtClassBody)?.parent as? KtClassOrObject

ultimate/src/org/jetbrains/kotlin/idea/spring/el/KotlinSpringELInjector.kt

@@ -33,7 +33,7 @@ import org.jetbrains.kotlin.psi.KtAnnotationEntry
 import org.jetbrains.kotlin.psi.KtStringTemplateExpression
 import org.jetbrains.kotlin.psi.KtValueArgument
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
-import org.jetbrains.kotlin.psi.psiUtil.isPlain
+import org.jetbrains.kotlin.psi.psiUtil.isPlainWithEscapes
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 import org.jetbrains.kotlin.utils.ifEmpty
@@ -52,7 +52,7 @@ class KotlinSpringELInjector : MultiHostInjector {
 
     override fun getLanguagesToInject(registrar: MultiHostRegistrar, host: PsiElement) {
         if (host is KtStringTemplateExpression) {
-            if (!host.isPlain()) return
+            if (!host.isPlainWithEscapes()) return
 
             val argument = host.parent as? KtValueArgument ?: return
             val entry = argument.getStrictParentOfType<KtAnnotationEntry>() ?: return