question: private SnmpPduPacket makeResponsePdu ( SnmpPduPacket reqPdu , Object userData ) { SnmpAdaptorServer snmpServer = ( SnmpAdaptorServer ) adaptorServer ; SnmpPduPacket respPdu = null ; snmpServer . updateRequestCounters ( reqPdu . type ) ; if ( reqPdu . varBindList != null ) snmpServer . updateVarCounters ( reqPdu . type , reqPdu . varBindList . length ) ; if ( checkPduType ( reqPdu ) ) { respPdu = checkAcl ( reqPdu ) ; if ( respPdu == null ) { if ( mibs . size ( ) < 1 ) { if ( SNMP_ADAPTOR_LOGGER . isLoggable ( Level . FINER ) ) { SNMP_ADAPTOR_LOGGER . logp ( Level . FINER , dbgTag , "makeResponsePdu" , "Request " + reqPdu . requestId + " received but no MIB registered." ) ; } return makeNoMibErrorPdu ( ( SnmpPduRequest ) reqPdu , userData ) ; } switch ( reqPdu . type ) { case SnmpPduPacket . pduGetRequestPdu : case SnmpPduPacket . pduGetNextRequestPdu : case SnmpPduPacket . pduSetRequestPdu : respPdu = makeGetSetResponsePdu ( ( SnmpPduRequest ) reqPdu , userData ) ; break ; case SnmpPduPacket . pduGetBulkRequestPdu : respPdu = makeGetBulkResponsePdu ( ( SnmpPduBulk ) reqPdu , userData ) ; break ; } } else { if ( ! snmpServer . getAuthRespEnabled ( ) ) { respPdu = null ; } if ( snmpServer . getAuthTrapEnabled ( ) ) { try { snmpServer . snmpV1Trap ( SnmpPduTrap . trapAuthenticationFailure , 0 , new SnmpVarBindList ( ) ) ; } catch ( Exception x ) { if ( SNMP_ADAPTOR_LOGGER . isLoggable ( Level . FINEST ) ) { SNMP_ADAPTOR_LOGGER . logp ( Level . FINEST , dbgTag , "makeResponsePdu" , "Failure when sending authentication trap" , x ) ; } } } } } return respPdu ; }
target:  Here we make a response pdu from a request pdu. We return null if there is no pdu to reply.