-- binary
00 03 # class
0a # type/masked
04 # length
12 34 56 78 # value
-- python
ofp.oxm.bsn_l3_src_class_id(0x12345678)
-- c
obj = of_oxm_bsn_l3_src_class_id_new(OF_VERSION_1_3);
of_oxm_bsn_l3_src_class_id_value_set(obj, 0x12345678);
-- java
builder.setValue(ClassId.of(0x12345678))