question: private int _convertSurrogate ( int firstPart , int secondPart ) { if ( secondPart < SURR2_FIRST || secondPart > SURR2_LAST ) { throw new IllegalArgumentException ( "Broken surrogate pair: first char 0x" + Integer . toHexString ( firstPart ) + ", second 0x" + Integer . toHexString ( secondPart ) + "; illegal combination" ) ; } return 0x10000 + ( ( firstPart - SURR1_FIRST ) << 10 ) + ( secondPart - SURR2_FIRST ) ; }
target:  Method called to calculate UTF codepoint, from a surrogate pair.