As part of securing non-public APIs, it appears that a critical piece of the MethodHandle API has been blocked without allowing internal classes to use it.

Attempting to use the MethodHandles.constant method, which returns a MethodHandle that returns a constant value, you will see the following error:

java.lang.AssertionError: java.lang.NoSuchMethodException: java.lang.invoke.MethodHandles.identity [boolean]
	at java.lang.invoke.MethodHandles.makeIdentity(MethodHandles.java:2930)
	at java.lang.invoke.MethodHandles.identity(MethodHandles.java:2864)
	at java.lang.invoke.MethodHandles.constant(MethodHandles.java:2841)

The underlying cause is that MethodHandles.makeIdentity appears to reflectively access a restricted MethodHandles.identity variant:

Caused by: java.lang.NoSuchMethodException: java.lang.invoke.MethodHandles.identity [boolean]
	at java.lang.Class.getMethod(Class.java:2103)
	at java.lang.Class.getDeclaredMethod(Class.java:2081)
	at java.lang.invoke.MethodHandles$Lookup.findStatic(MethodHandles.java:837)
	at java.lang.invoke.MethodHandles.makeIdentity(MethodHandles.java:2928)

I could not find the exact source that corresponds to MethodHandles.java:2928 here.

I believe this access of MethodHandles.identity should be allowed, or perhaps the implementation of MethodHandles.makeIdentity needs to be updated to a version that does not reflectively access (via Lookup) the identity method.

Note this also affects other java.lang.invoke classes that depend on the public MethodHandles.identity; specifically, the SwitchPoint class uses this call path in its class initialization, so this restriction prevents SwitchPoint from being loaded at all.

This was discovered while updating JRuby and its Android framework "Ruboto" for Android level 33. JRuby uses invokedynamic and method handles extensively.

Issue 281448905

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