dap4/d4servlet/src/main/java/dap4/servlet/SerialWriter.java
public void
    outputBytes(byte[] bytes, int start, int count)
            throws IOException
    {
        if(DUMPDATA) {
            System.err.printf("output %d/%d:", start, count);
            for(int i = 0; i < count; i++) {
                System.err.printf(" %02x", bytes[i]);
            }
            System.err.println("");
            System.err.flush();
        }
        output.write(bytes, start, count);
    }
public void
    outputBytes(byte[] bytes, int start, int count)
            throws IOException
    {
        if(DUMPDATA) {
            System.err.printf("output %d/%d:", start, count);
            for(int i = 0; i < count; i++) {
                System.err.printf(" %02x", bytes[i]);
            }
            System.err.println("");
            System.err.flush();
        }
        output.write(bytes, start, count);
    }
Deliberate choke point for debugging

@param bytes
@param start
@param count
@throws IOException