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