-- binary
06 18 # version, type
00 18 # length
12 34 56 78 # xid
00 00 00 02 # role (OFPCR_ROLE_MASTER)
00 01 # short_id
00 00 # pad
00 00 00 00 00 00 00 01 # generation_id
-- java
builder
        .setXid(0x12345678)
        .setRole(OFControllerRole.ROLE_MASTER)
        .setShortId(1)
        .setGenerationId(U64.of(1))
        .build()