private void write(STATUS status, byte[] bytes) {
        try {
            int len = bytes.length;
            output.write(status.getByte());
            output.writeInt(len);
            output.write(bytes);
            output.flush();
        } catch (IOException e) {
            LOG.error("problem writing data (forking process shutdown?)", e);
            exit(1);
        }
    }
returns stack trace if there was a container exception or empty string
if there was no stacktrace

@param t
@param metadataList
@return
tika-core/src/main/java/org/apache/tika/pipes/PipesServer.java