code: protected final int indexOf(@Nullable final CharSequence value) {
          if (value != null && getEntryValues() != null) {
              for (int i = getEntryValues().length - 1; i >= 0; i--) {
                  if (getEntryValues()[i].equals(value)) {
                      return i;
                  }
              }
          }
  
          return -1;
      }
docs: Return the index of the entry, a specific value corresponds to.
  
  @param value
  The value of the entry, whose index should be returned, as an instance of the type
  {@link CharSequence}
  @return The index of the entry, the given value corresponds to, as an {@link Integer} value
  or -1 if there is no such entry