Remove the @PublishedApi that are no longer needed (#4089)

According to @mvicsokolova, the following entry points are not
used by IDEA since 2020:

kotlinx.coroutines.debug.internal.StackTraceFrame
	field callerFrame
	field stackTraceElement
kotlinx.coroutines.StandaloneCoroutine
	field _state
	field context
kotlinx.coroutines.ChildContinuation
	field child
kotlinx.coroutines.CancellableContinuationImpl
	field _decision
	field delegate
	field resumeMode
	field submissionTime
	field context
kotlinx.coroutines.DispatchedContinuation
	field continuation

This leaves only the following *internal* entry points:

kotlinx.coroutines.debug.internal.DebugCoroutineInfo
	method getCreationStackTrace()
	method getState()
	method lastObservedStackTrace()
	field context
	field sequenceNumber
	field lastObservedFrame
	field lastObservedThread
kotlinx.coroutines.debug.internal.DebugCoroutineInfoImpl
	method getCreationStackTrace()
	method getContext()
	field lastObservedThread
	field _state
	field _lastObservedFrame
	field sequenceNumber
kotlinx.coroutines.debug.internal.DebugProbesImpl
	field INSTANCE
	method isInstalled$kotlinx_coroutines_debug()
	method isInstalled$kotlinx_coroutines_core()
	method enhanceStackTraceWithThreadDump()
	method dumpCoroutinesInfo()
	method dumpCoroutinesInfoAsJsonAndReferences()
	method enhanceStackTraceWithThreadDumpAsJson()
kotlinx.coroutines.debug.internal.DebugProbesImpl$CoroutineOwner
	field info
kotlinx.coroutines.CoroutineId
	field Key
	method getId()

... the following *public* entry points:

kotlinx.coroutines.CoroutineName
	field Key
	method getName()
kotlinx.coroutines.Job
	field Key
kotlinx.coroutines.CoroutineDispatcher
	field Key

... and these entry points outside of the library:

kotlin.coroutines.CombinedContext
	method get()
kotlin.coroutines.jvm.internal.DebugMetadataKt
	method getStackTraceElement()
	method getSpilledVariableFieldMapping()

This commit updates the comments and removes the extraneous
`@PublishedApi` annotations, giving us more flexibility to change
code.

Author: dkhalanskyjb

kotlinx-coroutines-core/api/kotlinx-coroutines-core.api

@@ -51,7 +51,7 @@ public final class kotlinx/coroutines/CancellableContinuation$DefaultImpls {
 	public static synthetic fun tryResume$default (Lkotlinx/coroutines/CancellableContinuation;Ljava/lang/Object;Ljava/lang/Object;ILjava/lang/Object;)Ljava/lang/Object;
 }
 
-public class kotlinx/coroutines/CancellableContinuationImpl : kotlinx/coroutines/DispatchedTask, kotlin/coroutines/jvm/internal/CoroutineStackFrame, kotlinx/coroutines/CancellableContinuation, kotlinx/coroutines/Waiter {
+public class kotlinx/coroutines/CancellableContinuationImpl : kotlin/coroutines/jvm/internal/CoroutineStackFrame, kotlinx/coroutines/CancellableContinuation, kotlinx/coroutines/Waiter {
 	public fun <init> (Lkotlin/coroutines/Continuation;I)V
 	public final fun callCancelHandler (Lkotlinx/coroutines/CancelHandler;Ljava/lang/Throwable;)V
 	public final fun callOnCancellation (Lkotlin/jvm/functions/Function1;Ljava/lang/Throwable;)V
@@ -84,12 +84,6 @@ public final class kotlinx/coroutines/CancellableContinuationKt {
 	public static final fun suspendCancellableCoroutine (Lkotlin/jvm/functions/Function1;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 }
 
-public final class kotlinx/coroutines/ChildContinuation {
-	public final field child Lkotlinx/coroutines/CancellableContinuationImpl;
-	public fun <init> (Lkotlinx/coroutines/CancellableContinuationImpl;)V
-	public fun invoke (Ljava/lang/Throwable;)V
-}
-
 public abstract interface class kotlinx/coroutines/ChildHandle : kotlinx/coroutines/DisposableHandle {
 	public abstract fun childCancelled (Ljava/lang/Throwable;)Z
 	public abstract fun getParent ()Lkotlinx/coroutines/Job;
@@ -318,15 +312,6 @@ public final class kotlinx/coroutines/DelayKt {
 public abstract interface annotation class kotlinx/coroutines/DelicateCoroutinesApi : java/lang/annotation/Annotation {
 }
 
-public final class kotlinx/coroutines/DispatchedCoroutine {
-	public static final synthetic fun get_decision$volatile$FU$kotlinx_coroutines_core ()Ljava/util/concurrent/atomic/AtomicIntegerFieldUpdater;
-}
-
-public abstract class kotlinx/coroutines/DispatchedTask : kotlinx/coroutines/scheduling/Task {
-	public field resumeMode I
-	public final fun run ()V
-}
-
 public final class kotlinx/coroutines/DispatchedTaskKt {
 	public static final field MODE_CANCELLABLE I
 }
@@ -970,12 +955,6 @@ public final class kotlinx/coroutines/debug/internal/DebuggerInfo : java/io/Seri
 	public final fun getState ()Ljava/lang/String;
 }
 
-public final class kotlinx/coroutines/debug/internal/StackTraceFrame : kotlin/coroutines/jvm/internal/CoroutineStackFrame {
-	public final field stackTraceElement Ljava/lang/StackTraceElement;
-	public fun getCallerFrame ()Lkotlin/coroutines/jvm/internal/CoroutineStackFrame;
-	public fun getStackTraceElement ()Ljava/lang/StackTraceElement;
-}
-
 public abstract class kotlinx/coroutines/flow/AbstractFlow : kotlinx/coroutines/flow/CancellableFlow, kotlinx/coroutines/flow/Flow {
 	public fun <init> ()V
 	public final fun collect (Lkotlinx/coroutines/flow/FlowCollector;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
@@ -1287,10 +1266,6 @@ public class kotlinx/coroutines/scheduling/ExperimentalCoroutineDispatcher : kot
 	public fun toString ()Ljava/lang/String;
 }
 
-public abstract class kotlinx/coroutines/scheduling/Task : java/lang/Runnable {
-	public field submissionTime J
-}
-
 public final class kotlinx/coroutines/selects/OnTimeoutKt {
 	public static final fun onTimeout (Lkotlinx/coroutines/selects/SelectBuilder;JLkotlin/jvm/functions/Function1;)V
 	public static final fun onTimeout-8Mi8wO0 (Lkotlinx/coroutines/selects/SelectBuilder;JLkotlin/jvm/functions/Function1;)V

kotlinx-coroutines-core/common/src/Builders.common.kt

@@ -214,16 +214,13 @@ private const val SUSPENDED = 1
 private const val RESUMED = 2
 
 // Used by withContext when context dispatcher changes
-@PublishedApi
-internal class DispatchedCoroutine<in T> internal constructor(
+internal class DispatchedCoroutine<in T>(
     context: CoroutineContext,
     uCont: Continuation<T>
 ) : ScopeCoroutine<T>(context, uCont) {
     // this is copy-and-paste of a decision state machine inside AbstractionContinuation
     // todo: we may some-how abstract it via inline class
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
-    @JvmField
-    public val _decision = atomic(UNDECIDED)
+    private val _decision = atomic(UNDECIDED)
 
     private fun trySuspend(): Boolean {
         _decision.loop { decision ->

kotlinx-coroutines-core/common/src/CancellableContinuationImpl.kt

@@ -678,3 +678,12 @@ private data class CompletedContinuation(
         onCancellation?.let { cont.callOnCancellation(it, cause) }
     }
 }
+
+// Same as ChildHandleNode, but for cancellable continuation
+private class ChildContinuation(
+    @JvmField val child: CancellableContinuationImpl<*>
+) : JobCancellingNode() {
+    override fun invoke(cause: Throwable?) {
+        child.parentCancelled(child.getContinuationCancellationCause(job))
+    }
+}

kotlinx-coroutines-core/common/src/JobSupport.kt

@@ -121,7 +121,6 @@ public open class JobSupport constructor(active: Boolean) : Job, ChildJob, Paren
      */
 
     // Note: use shared objects while we have no listeners
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
     private val _state = atomic<Any?>(if (active) EMPTY_ACTIVE else EMPTY_NEW)
 
     private val _parentHandle = atomic<ChildHandle?>(null)
@@ -1439,22 +1438,10 @@ private class InvokeOnCancelling(
     }
 }
 
-internal class ChildHandleNode(
+private class ChildHandleNode(
     @JvmField val childJob: ChildJob
 ) : JobCancellingNode(), ChildHandle {
     override val parent: Job get() = job
     override fun invoke(cause: Throwable?) = childJob.parentCancelled(job)
     override fun childCancelled(cause: Throwable): Boolean = job.childCancelled(cause)
 }
-
-// Same as ChildHandleNode, but for cancellable continuation
-@PublishedApi
-internal class ChildContinuation(
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
-    @JvmField val child: CancellableContinuationImpl<*>
-) : JobCancellingNode() {
-    override fun invoke(cause: Throwable?) {
-        child.parentCancelled(child.getContinuationCancellationCause(job))
-    }
-}
-

kotlinx-coroutines-core/common/src/internal/DispatchedContinuation.kt

@@ -9,10 +9,8 @@ private val UNDEFINED = Symbol("UNDEFINED")
 @JvmField
 internal val REUSABLE_CLAIMED = Symbol("REUSABLE_CLAIMED")
 
-@PublishedApi
 internal class DispatchedContinuation<in T>(
     @JvmField internal val dispatcher: CoroutineDispatcher,
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
     @JvmField val continuation: Continuation<T>
 ) : DispatchedTask<T>(MODE_UNINITIALIZED), CoroutineStackFrame, Continuation<T> by continuation {
     @JvmField

kotlinx-coroutines-core/common/src/internal/DispatchedTask.kt

@@ -43,10 +43,8 @@ internal const val MODE_UNINITIALIZED = -1
 internal val Int.isCancellableMode get() = this == MODE_CANCELLABLE || this == MODE_CANCELLABLE_REUSABLE
 internal val Int.isReusableMode get() = this == MODE_CANCELLABLE_REUSABLE
 
-@PublishedApi
 internal abstract class DispatchedTask<in T> internal constructor(
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
-    @JvmField public var resumeMode: Int
+    @JvmField var resumeMode: Int
 ) : SchedulerTask() {
     internal abstract val delegate: Continuation<T>
 

kotlinx-coroutines-core/jvm/src/debug/internal/DebugCoroutineInfoImpl.kt

@@ -30,8 +30,10 @@ internal class DebugCoroutineInfoImpl internal constructor(
      */
     private val _context = WeakReference(context)
     public val context: CoroutineContext? // can be null when the coroutine was already garbage-collected
+        // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
         get() = _context.get()
 
+    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
     public val creationStackTrace: List<StackTraceElement> get() = creationStackTrace()
 
     /**

kotlinx-coroutines-core/jvm/src/debug/internal/StackTraceFrame.kt

@@ -5,11 +5,9 @@ import kotlin.coroutines.jvm.internal.*
 /**
  * A stack-trace represented as [CoroutineStackFrame].
  */
-@PublishedApi
-internal class StackTraceFrame internal constructor(
+internal class StackTraceFrame(
     override val callerFrame: CoroutineStackFrame?,
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
-    @JvmField public val stackTraceElement: StackTraceElement
+    private val stackTraceElement: StackTraceElement
 ) : CoroutineStackFrame {
     override fun getStackTraceElement(): StackTraceElement = stackTraceElement
 }

kotlinx-coroutines-core/jvm/src/scheduling/Tasks.kt

@@ -75,12 +75,9 @@ internal val NonBlockingContext: TaskContext = TaskContextImpl(TASK_NON_BLOCKING
 @JvmField
 internal val BlockingContext: TaskContext = TaskContextImpl(TASK_PROBABLY_BLOCKING)
 
-@PublishedApi
-internal abstract class Task internal constructor(
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
+internal abstract class Task(
     @JvmField var submissionTime: Long,
-    // Used by the IDEA debugger via reflection and must be kept binary-compatible, see KTIJ-24102
-    @JvmField internal var taskContext: TaskContext
+    @JvmField var taskContext: TaskContext
 ) : Runnable {
     internal constructor() : this(0, NonBlockingContext)
     internal inline val mode: Int get() = taskContext.taskMode // TASK_XXX

kotlinx-coroutines-core/jvm/test/ReusableCancellableContinuationTest.kt

@@ -210,6 +210,9 @@ class ReusableCancellableContinuationTest : TestBase() {
         for (value in channel) {
             delay(1)
         }
-        FieldWalker.assertReachableCount(1, coroutineContext[Job]) { it is ChildContinuation }
+        FieldWalker.assertReachableCount(1, coroutineContext[Job]) {
+            // could be `it is ChildContinuation` if `ChildContinuation` wasn't private
+            it::class.simpleName == "ChildContinuation"
+        }
     }
 }