question: @ SuppressWarnings ( "unchecked" ) public boolean containsKey ( Object key ) { Segment < K , V > s ; HashEntry < K , V > [ ] tab ; int h = hash ( key . hashCode ( ) ) ; long u = ( ( ( h > > > segmentShift ) & segmentMask ) << SSHIFT ) + SBASE ; if ( ( s = ( Segment < K , V > ) UNSAFE . getObjectVolatile ( segments , u ) ) != null && ( tab = s . table ) != null ) { for ( HashEntry < K , V > e = ( HashEntry < K , V > ) UNSAFE . getObjectVolatile ( tab , ( ( long ) ( ( ( tab . length - 1 ) & h ) ) << TSHIFT ) + TBASE ) ; e != null ; e = e . next ) { K k ; if ( ( k = e . key ) == key || ( e . hash == h && key . equals ( k ) ) ) return true ; } } return false ; }
target:  Tests if the specified object is a key in this table.