RFR: 8333748: javap crash - Fatal error: Unmatched bit position 0x2 for location CLASS [v4]

[Chen Liang]

> Currently, javap crashes for class files that have set non-zero values for undefined access flag bits, as `java.lang.reflect.AccessFlag.maskToAccessFlag` and `java.lang.classfile.AccessFlags.flags` fail. In contrast, the JVMS, though asking for these bits to be set to 0, requires VM to proceed and ignore these bits. javap should emulate the VM behavior and proceed rendering, ignoring these undefined bits.
> 
> In addition, a few bytecode generation utilities in the JDK set unused bits, such as in `java.lang.invoke.MethodHandleImpl.BindCaller#generateInvokerTemplate` and `java.lang.invoke.GenerateJLIClassesHelper#generateCodeBytesForLFs`. Those can be updated in a later cleanup.

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  Improved error message

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19708/files
  - new: https://git.openjdk.org/jdk/pull/19708/files/0f3e1a97..c8eee028

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19708&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19708&range=02-03

  Stats: 20 lines in 2 files changed: 16 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/19708.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19708/head:pull/19708

PR: https://git.openjdk.org/jdk/pull/19708