Below are the JAVA API to inject FCS Errors in streamblock:
System.out.println("Configuring stream block ...");
String hStreamBlock = stc.Create("streamBlock", hPortTx);
sm.clear();
sm.put("insertSig", "true");
sm.put("frameConfig", "");
sm.put("frameLengthMode", "FIXED");
sm.put("maxFrameLength", "1200");
sm.put("FixedFrameLength", "256");
sm.put("EnableFcsErrorInsertion", "TRUE");
stc.Config(hStreamBlock, sm);