code: @Override
      public void registerEarlyRead(InterChannelCallback cb) {
          // LI4335.2
          if (null == cb) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
                  Tr.debug(tc, "registerEarlyRead: Invalid null callback as input.");
              }
              throw new IllegalArgumentException("Callback is null");
          }
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "App channel requesting early response read on " + getVC());
          }
          this.bEarlyReads = true;
          startEarlyRead(cb, true);
      }
docs: /*
  @see com.ibm.wsspi.http.channel.outbound.HttpOutboundServiceContext#
  registerEarlyRead(com.ibm.wsspi.channelfw.InterChannelCallback)