Make KtLightModifierList behave like light element and check it in tests

compiler/light-classes/src/org/jetbrains/kotlin/asJava/KtLightModifierListWithExplicitModifiers.kt

@@ -16,12 +16,14 @@
 
 package org.jetbrains.kotlin.asJava
 
+import com.intellij.openapi.util.TextRange
 import com.intellij.psi.*
 import com.intellij.psi.impl.light.LightModifierList
 import com.intellij.psi.util.CachedValue
 import com.intellij.psi.util.CachedValueProvider
 import com.intellij.psi.util.CachedValuesManager
 import com.intellij.psi.util.PsiModificationTracker
+import com.intellij.util.ArrayUtil
 import org.jetbrains.annotations.NonNls
 import org.jetbrains.kotlin.idea.KotlinLanguage
 import org.jetbrains.kotlin.psi.KtAnnotationEntry
@@ -52,7 +54,7 @@ abstract class KtLightModifierListWithExplicitModifiers(
 class KtLightModifierList(
         private val delegate: PsiModifierList,
         private val owner: PsiModifierListOwner
-): PsiModifierList by delegate {
+) : PsiModifierList by delegate {
     private val _annotations by lazy { computeAnnotations(this, delegate) }
 
     override fun getAnnotations(): Array<out PsiAnnotation> = _annotations.value
@@ -62,6 +64,28 @@ class KtLightModifierList(
     override fun addAnnotation(@NonNls qualifiedName: String) = delegate.addAnnotation(qualifiedName)
 
     override fun getParent() = owner
+
+    override fun getText(): String? = ""
+
+    override fun getLanguage() = KotlinLanguage.INSTANCE
+    override fun getTextRange() = TextRange.EMPTY_RANGE
+    override fun getStartOffsetInParent() = -1
+    override fun getTextLength() = 0
+    override fun getPrevSibling(): PsiElement? = null
+    override fun getNextSibling(): PsiElement? = null
+    override fun findElementAt(offset: Int): PsiElement? = null
+    override fun findReferenceAt(offset: Int): PsiReference? = null
+    override fun getTextOffset() = -1
+    override fun isWritable() = false
+    override fun isPhysical() = false
+    override fun textToCharArray(): CharArray = ArrayUtil.EMPTY_CHAR_ARRAY;
+    override fun textMatches(text: CharSequence): Boolean = getText() == text.toString()
+    override fun textMatches(element: PsiElement): Boolean = text == element.text
+    override fun textContains(c: Char): Boolean = text?.contains(c) ?: false
+    override fun copy(): PsiElement = KtLightModifierList(delegate, owner)
+    override fun getReferences() = PsiReference.EMPTY_ARRAY
+    override fun isEquivalentTo(another: PsiElement?) =
+            another is KtLightModifierList && delegate == another.delegate && owner == owner
 }
 
 internal fun computeAnnotations(lightElement: PsiModifierList,

idea/tests/org/jetbrains/kotlin/idea/caches/resolve/PsiElementChecker.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.idea.caches.resolve
 import com.intellij.openapi.util.Key
 import com.intellij.psi.*
 import org.jetbrains.kotlin.asJava.KtLightElement
+import org.jetbrains.kotlin.asJava.KtLightModifierList
 import org.jetbrains.kotlin.idea.KotlinLanguage
 import org.junit.Assert
 
@@ -39,7 +40,7 @@ object PsiElementChecker {
     }
 
     private fun checkPsiElement(element: PsiElement) {
-        if (element !is KtLightElement<*, *>) return
+        if (element !is KtLightElement<*, *> && element !is KtLightModifierList) return
 
         if (element is PsiModifierListOwner) {
             val modifierList = element.modifierList