Improve condy (constant dynamic) support

[kriegaex]

Fixes https://issues.apache.org/jira/browse/BCEL-362.

There was a problem when processing JaCoCo-instrumented code with BCEL, e.g. when passing it through example class JasminVisitor, causing

java.lang.ClassCastException: class org.apache.bcel.classfile.ConstantMethodref cannot be cast to class org.apache.bcel.classfile.ConstantClass (org.apache.bcel.classfile.ConstantMethodref and org.apache.bcel.classfile.ConstantClass are in unnamed module of loader 'app')
    at org.apache.bcel.generic.ConstantPoolGen.<init>(ConstantPoolGen.java:153)
    at org.apache.bcel.generic.ConstantPoolGen.<init>(ConstantPoolGen.java:211)
    at de.example.JasminVisitor.<init>(JasminVisitor.java:70)

[codecov-commenter]

Codecov Report

Merging #139 (735abe4) into master (8b0b168) will increase coverage by 0.04%.
The diff coverage is 33.33%.

@@             Coverage Diff              @@
##             master     #139      +/-   ##
============================================
+ Coverage     44.08%   44.12%   +0.04%     
- Complexity     2521     2527       +6     
============================================
  Files           362      362              
  Lines         16322    16327       +5     
  Branches       2126     2127       +1     
============================================
+ Hits           7195     7205      +10     
+ Misses         8398     8394       -4     
+ Partials        729      728       -1     

Impacted Files	Coverage Δ
...n/java/org/apache/bcel/classfile/ConstantPool.java	64.66% <0.00%> (-2.01%)	⬇️
.../java/org/apache/bcel/generic/ConstantPoolGen.java	68.98% <100.00%> (+0.21%)	⬆️
src/main/java/org/apache/bcel/util/Class2HTML.java	53.19% <0.00%> (-0.50%)	⬇️
src/main/java/org/apache/bcel/Repository.java	14.28% <0.00%> (ø)
src/main/java/org/apache/bcel/util/CodeHTML.java	50.17% <0.00%> (ø)
src/main/java/org/apache/bcel/util/MethodHTML.java	56.06% <0.00%> (ø)
...c/main/java/org/apache/bcel/util/ConstantHTML.java	95.04% <0.00%> (ø)
.../main/java/org/apache/bcel/util/AttributeHTML.java	56.38% <0.00%> (ø)
src/main/java/org/apache/bcel/util/ClassPath.java	42.63% <0.00%> (+1.16%)	⬆️
.../main/java/org/apache/bcel/classfile/Constant.java	57.14% <0.00%> (+2.38%)	⬆️
... and 1 more

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[garydgregory]

Hello @kriegaex,

Thank you for you PR!

You'll need update this PR with some kind of test, otherwise, this is a regression waiting to happen. It could be as simple as parsing a class file that fails without applying the "main" side for the PR. The test should reflect what you say happens, namely:

java.lang.ClassCastException: class org.apache.bcel.classfile.ConstantMethodref cannot be cast to class org.apache.bcel.classfile.ConstantClass (org.apache.bcel.classfile.ConstantMethodref and org.apache.bcel.classfile.ConstantClass are in unnamed module of loader 'app')
    at org.apache.bcel.generic.ConstantPoolGen.<init>(ConstantPoolGen.java:153)
    at org.apache.bcel.generic.ConstantPoolGen.<init>(ConstantPoolGen.java:211)
    ...

Take notice that Codecov commented that coverage has decreased due to this PR not being tested:

- Coverage     44.08%   44.08%   -0.01%  

In fact, that is often what I do to validate a PR:

• Apply the test side of the PR,
• Watch the test fail,
• Apply the main side of the PR, and
• Watch the test pass.
• Merge the PR

Thank you again for helping out 😄

[kriegaex]

So, instead of being happy that someone provides a PR at all after me having begged the contributors for a bugfix, and writing a test by yourself, now the PR I was asked to contribute before is not good enough still, and I should provide a test, too? That is quite an interesting experience with this project.

What exactly do maintainers do around here? Simply wait for users to do everything? Actually, I do have a test, but it requires JaCoCo in my Maven project. I checked whether you have a Maven Invoker test suite, but you do not. So there is no easy way to provide a test without digging into BCEL's intestines and writing a separate test, similar to the ones you already have with extra precompiled class files that can be processed by BCEL. I do not have the cycles for that.

Actually, I only wanted to fix a problem in AspectJ, asking the BCEL team for help. I got none, so I had to fix it myself in AspectJ. I was even nice enough to provide a bugfix for the upstream project, and now that is not good enough. Uh-huh.

[kriegaex]

FWIW, I added a test case - not with the goal to increase coverage but to prevent future regressions. Reverse the order of the two commits, and the test before the fix will fail.