code: @Override
      public void sawOpcode(int seen) {
  
          if ((seen == Const.INVOKEINTERFACE) || (seen == Const.INVOKEVIRTUAL) || (seen == Const.INVOKESPECIAL) || (seen == Const.INVOKESTATIC)) {
              String clsName = getClassConstantOperand();
              String mName = getNameConstantOperand();
              String methodInfo = clsName + ':' + mName;
              String thisMethodInfo = (clsName.equals(getClassName())) ? (mName + ':' + methodSig) : "0";
  
              if (expensiveCalls.contains(methodInfo) || expensiveThisCalls.contains(thisMethodInfo)) {
                  if (isListenerMethod) {
                      bugReporter.reportBug(new BugInstance(this, BugType.SG_SLUGGISH_GUI.name(), NORMAL_PRIORITY).addClass(this)
                              .addMethod(this.getClassContext().getJavaClass(), listenerCode.get(this.getCode())));
                  } else {
                      expensiveThisCalls.add(getMethodName() + ':' + getMethodSig());
                  }
                  throw new StopOpcodeParsingException();
              }
          }
      }
docs: overrides the visitor to look for the execution of expensive calls
  
  @param seen
  the currently parsed opcode