FIR/UAST: commonize UnknownKotlinExpression

plugins/uast-kotlin-base/src/org/jetbrains/uast/kotlin/expressions/UnknownKotlinExpression.kt

@@ -0,0 +1,17 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.uast.kotlin
+
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.uast.UElement
+import org.jetbrains.uast.UExpression
+
+class UnknownKotlinExpression(
+    override val sourcePsi: KtExpression,
+    givenParent: UElement?
+) : KotlinAbstractUExpression(givenParent), UExpression {
+    override fun asLogString() = "[!] UnknownKotlinExpression ($sourcePsi)"
+}