code: @Override
      public void sawOpcode(int seen) {
          stack.precomputation(this);
  
          switch (seen) {
              case Const.INVOKESTATIC: {
                  String className = getClassConstantOperand();
                  for (Backports backport : BACKPORTS) {
                      if (className.startsWith(backport.getPathPrefix())) {
                          if (clsVersion >= backport.getMinimumJDK()) {
                              reportBug(backport.getLibrary());
                              break;
                          }
                      }
                  }
              }
              break;
  
              case Const.INVOKESPECIAL: {
                  String className = getClassConstantOperand();
                  String methodName = getNameConstantOperand();
                  for (Backports backport : BACKPORTS) {
                      if (Values.CONSTRUCTOR.equals(methodName) && className.startsWith(backport.getPathPrefix()) && (clsVersion >= backport.getMinimumJDK())) {
                          reportBug(backport.getLibrary());
                          break;
                      }
                  }
              }
              break;
  
              default:
              break;
          }
      }
docs: overrides the visitor to look for method calls to the emory backport concurrent library, or threeten bp library when the now built-in versions are
  available
  
  @param seen
  the currently parsed opcode