write
Writes a long to this sink in hexadecimal form (i.e., as a string in base 16).
Buffer buffer = new Buffer();
buffer.writeHexadecimalUnsignedLong(65535L);
buffer.writeByte(' ');
buffer.writeHexadecimalUnsignedLong(0xcafebabeL);
buffer.writeByte(' ');
buffer.writeHexadecimalUnsignedLong(0x10L);
assertEquals("ffff cafebabe 10", buffer.readUtf8());