@Override
  public void filter(Throwable throwable) {
    filter(throwable, newSetFromMap(new IdentityHashMap<>()));
  }
Filters an exception's stack trace. Removes internal Groovy and Spock methods, and
restores the original names of feature methods (as specified in source code).
Stack trace elements below a feature/fixture method invocation are truncated.

@author Peter Niederwieser
spock-core/src/main/java/org/spockframework/runtime/StackTraceFilter.java