void setChunkException(RouterException exception) {
      if (chunkException == null || getPrecedenceLevel(exception.getErrorCode()) < getPrecedenceLevel(
          chunkException.getErrorCode())) {
        chunkException = exception;
      }
    }
Set the exception associated with this chunk operation.
First, if the current chunkException is null, directly set it as provided exception;
Second, if the chunkException exists but the precedence level of the provided exception's error code is smaller
than the precedence level of the chunkException's error code, then update the chunkException.
@param exception the {@link RouterException} to possibly set.
ambry-router/src/main/java/com/github/ambry/router/GetBlobOperation.java