VTA call graph: call sites in methods of abstract base classes have empty targets.

[michael-emmi]

Please examine each of the following points so that we can help you as soon and best as possible.

Describe the bug The call graph computed by Spark’s implementation of VTA does not include any targets for the call sites in methods of abstract base classes.

Input file See tests added in PR #1900

To reproduce Steps to reproduce the behavior: Run unit tests included in PR #1900 without the "include-abstract-classes:true" option proposed by PR #1900.

% mvn -Dtest=VtaCallGraphBaseClassTest -Dsurefire.failIfNoSpecifiedTests=false test

The call site of bar in foo should include bar as a target. Currently the target set is empty.

Expected behavior The callTargetsWithVta test should pass.

Stacktrace N/A

Additional context N/A