[uast] some UYieldExpression-related cleanups

GitOrigin-RevId: a044bf1a61b540a234a5db1e78a49e774d719bb4

uast/uast-common/src/org/jetbrains/uast/expressions/UYieldExpression.kt

@@ -1,16 +1,17 @@
 // Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.uast
 
-import org.jetbrains.uast.UExpression
-import org.jetbrains.uast.UJumpExpression
+import org.jetbrains.annotations.ApiStatus
 import org.jetbrains.uast.internal.acceptList
 import org.jetbrains.uast.internal.log
 import org.jetbrains.uast.visitor.UastTypedVisitor
 import org.jetbrains.uast.visitor.UastVisitor
 
 /**
- * Represents a `yield` expression.
+ * Represents an expression which return a value from the [USwitchExpression]-block.
+ * For instance the `yield` expression in Java 13.
  */
+@ApiStatus.Experimental
 interface UYieldExpression : UJumpExpression {
   val expression: UExpression?
 

uast/uast-common/src/org/jetbrains/uast/visitor/UastTypedVisitor.kt

@@ -69,6 +69,7 @@ interface UastTypedVisitor<in D, out R> {
   fun visitReturnExpression(node: UReturnExpression, data: D): R = visitExpression(node, data)
 
   fun visitBreakExpression(node: UBreakExpression, data: D): R = visitExpression(node, data)
+  @JvmDefault
   fun visitYieldExpression(node: UYieldExpression, data: D): R = visitExpression(node, data)
   fun visitContinueExpression(node: UContinueExpression, data: D): R = visitExpression(node, data)
   fun visitThrowExpression(node: UThrowExpression, data: D): R = visitExpression(node, data)

uast/uast-common/src/org/jetbrains/uast/visitor/UastVisitor.kt

@@ -52,6 +52,7 @@ interface UastVisitor {
   fun visitSuperExpression(node: USuperExpression): Boolean = visitExpression(node)
   fun visitReturnExpression(node: UReturnExpression): Boolean = visitExpression(node)
   fun visitBreakExpression(node: UBreakExpression): Boolean = visitExpression(node)
+  @JvmDefault
   fun visitYieldExpression(node: UYieldExpression): Boolean = visitExpression(node)
   fun visitContinueExpression(node: UContinueExpression): Boolean = visitExpression(node)
   fun visitThrowExpression(node: UThrowExpression): Boolean = visitExpression(node)
@@ -230,6 +231,7 @@ interface UastVisitor {
     afterVisitExpression(node)
   }
 
+  @JvmDefault
   fun afterVisitYieldExpression(node: UYieldExpression) {
     afterVisitExpression(node)
   }

uast/uast-java/src/org/jetbrains/uast/java/expressions/JavaUYieldExpression.kt

@@ -9,7 +9,7 @@ import org.jetbrains.uast.UYieldExpression
 
 class JavaUYieldExpression(
   override val sourcePsi: PsiYieldStatement,
-  val psiExpression: PsiExpression?,
+  private val psiExpression: PsiExpression?,
   givenParent: UElement?
 ) : JavaAbstractUExpression(givenParent), UYieldExpression {
   override val expression: UExpression? by lazy {