code: public int getAdditional(int codepoint, int column) {
          assert column >= 0;
          if (column >= m_additionalColumnsCount_) {
              return 0;
          }
          return m_additionalVectors_[m_additionalTrie_.get(codepoint) + column];
      }
docs: Gets the unicode additional properties.
  Java version of C u_getUnicodeProperties().
  @param codepoint codepoint whose additional properties is to be
  retrieved
  @param column The column index.
  @return unicode properties