code: public String getFragmentClassName(String injectorClassName,
        FragmentPackageName fragmentPackageName) {
      // Sanity check.
      Preconditions.checkArgument(!injectorClassName.contains("."),
          "The injector class must be a simple name, but it was \"%s\"", injectorClassName);
  
      // Note that the fragment package name is not actually included in the
      // fragment.  This reduces the length of the fragment's class name, which is
      // important because some systems have small limits on the maximum length of
      // a file (e.g., ~256 characters).  However, it means that other parts of
      // Gin must reference the fragment using its canonical class name, to avoid
      // ambiguity.
      return injectorClassName + "_fragment";
    }
docs: Computes the name of a single fragment of a Ginjector.
  
  @param injectorClassName the simple name of the injector's class (not
  including its package)