question: public static XContentType xContentType ( CharSequence content ) { int length = content . length ( ) < GUESS_HEADER_LENGTH ? content . length ( ) : GUESS_HEADER_LENGTH ; if ( length == 0 ) { return null ; } char first = content . charAt ( 0 ) ; if ( first == '{' ) { return XContentType . JSON ; } if ( length > 2 && first == SmileConstants . HEADER_BYTE_1 && content . charAt ( 1 ) == SmileConstants . HEADER_BYTE_2 && content . charAt ( 2 ) == SmileConstants . HEADER_BYTE_3 ) { return XContentType . SMILE ; } if ( length > 2 && first == '-' && content . charAt ( 1 ) == '-' && content . charAt ( 2 ) == '-' ) { return XContentType . YAML ; } for ( int i = 0 ; i < length ; i ++ ) { char c = content . charAt ( i ) ; if ( c == '{' ) { return XContentType . JSON ; } if ( Character . isWhitespace ( c ) == false ) { break ; } } return null ; }
target:  Guesses the content type based on the provided char sequence.