[jdk17] RFR: 8270025: DynamicCallSiteDesc::withArgs doesn't throw NPE [v2]

[Vicente Romero]

> Please review this PR that is fixing a mismatch between the implementation for method `java.lang.constant.DynamicCallSiteDesc::withArgs` and its implementation. I made a mistake while working on a recent CSR [JDK-8224985](https://bugs.openjdk.java.net/browse/JDK-8224985) and fixed the API but mistakenly thought that the implementation was in sync with the spec. This is why this change is also including a unit test of the API for `java.lang.constant.DynamicCallSiteDesc` modulo method `resolveCallSiteDesc` which is covered in test `IndyDescTest` in the same test suite. Also this change needs a CSR as while fixing the implementation of method `::withArgs` I realized that the API of the varargs overloaded version of method `::of` needed some rewording too as it is invoking the same private constructor `::withArgs` is invoking. So it didn't make sense for the API of one method to be more restrictive than the other. Please review also the accompanying CSR.
> 
> Thanks,
> Vicente

Vicente Romero has updated the pull request incrementally with one additional commit since the last revision:

  addressing review comments

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/242/files
  - new: https://git.openjdk.java.net/jdk17/pull/242/files/602a85c4..f7fddc99

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=242&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=242&range=00-01

  Stats: 42 lines in 1 file changed: 8 ins; 20 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/242.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/242/head:pull/242

PR: https://git.openjdk.java.net/jdk17/pull/242