@Override
  public Map<String, byte[]> getRequestAttributes() {
    if (this.requestAttributes == null) {
      if (header.getAttributeList().isEmpty()) {
        this.requestAttributes = Collections.emptyMap();
      } else {
        Map<String, byte[]> requestAttributes =
          Maps.newHashMapWithExpectedSize(header.getAttributeList().size());
        for (HBaseProtos.NameBytesPair nameBytesPair : header.getAttributeList()) {
          requestAttributes.put(nameBytesPair.getName(), nameBytesPair.getValue().toByteArray());
        }
        this.requestAttributes = requestAttributes;
      }
    }
    return this.requestAttributes;
  }
Call is done. Execution happened and we returned results to client. It is now safe to cleanup.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/ServerCall.java