public static boolean isDefaultTag(@Nullable String tag) {
    return DEFAULT_TAG.equals(tag);
  }
Returns {@code true} if {@code tag} is the default tag ({@code latest}); {@code false} if not.

@param tag the tag to check
@return {@code true} if {@code tag} is the default tag ({@code latest}); {@code false} if not
jib-core/src/main/java/com/google/cloud/tools/jib/api/ImageReference.java