code: public VersionInfo getAge(int codepoint)
      {
          int version = getAdditional(codepoint, 0) >> AGE_SHIFT_;
          return VersionInfo.getInstance(
                             (version >> FIRST_NIBBLE_SHIFT_) & LAST_NIBBLE_MASK_,
                             version & LAST_NIBBLE_MASK_, 0, 0);
      }
docs: <p>Get the "age" of the code point.</p>
  <p>The "age" is the Unicode version when the code point was first
  designated (as a non-character or for Private Use) or assigned a
  character.</p>
  <p>This can be useful to avoid emitting code points to receiving
  processes that do not accept newer characters.</p>
  <p>The data is from the UCD file DerivedAge.txt.</p>
  <p>This API does not check the validity of the codepoint.</p>
  @param codepoint The code point.
  @return the Unicode version number