Missing metric elements of openonu-go-adapter pm-data

It was observered several (not the same) metric elements are missing sporadically for Ethernet_UNI_History and Ethernet_Bridge_Port_History.

Example (for more see attached robot log file):

Received a slice with four metrics for Ethernet_UNI_History of one ONU:

1. Missing internal_mac_tx_error_counter in metrics:

'metrics':

{'alignment_error_counter': 6.0, 'buffer_overflows_on_rx': 5.0, 'buffer_overflows_on_tx': 79.0, 'carrier_sense_error_counter': 56.0, 'class_id': 24.0, 'deferred_tx_counter': 10.0, 'entity_id': 258.0, 'excessive_collision_counter': 66.0, 'fcs_errors': 60.0, 'frames_too_long': 22.0, 'internal_mac_rx_error_counter': 20.0, 'interval_end_time': 0.0, 'late_collision_counter': 23.0, 'multiple_collisions_frame_counter': 37.0, 'single_collision_frame_counter': 47.0, 'sqe_counter': 47.0}

2. Missing deferred_tx_counter in metrics:

'metrics':

{'alignment_error_counter': 76.0, 'buffer_overflows_on_rx': 66.0, 'buffer_overflows_on_tx': 19.0, 'carrier_sense_error_counter': 84.0, 'class_id': 24.0, 'entity_id': 259.0, 'excessive_collision_counter': 51.0, 'fcs_errors': 38.0, 'frames_too_long': 74.0, 'internal_mac_rx_error_counter': 84.0, 'internal_mac_tx_error_counter': 66.0, 'interval_end_time': 0.0, 'late_collision_counter': 5.0, 'multiple_collisions_frame_counter': 12.0, 'single_collision_frame_counter': 70.0, 'sqe_counter': 39.0}

3. Missing fcs_errors and internal_mac_rx_error_counter in metrics:

'metrics':

{'alignment_error_counter': 50.0, 'buffer_overflows_on_rx': 3.0, 'buffer_overflows_on_tx': 0.0, 'carrier_sense_error_counter': 92.0, 'class_id': 24.0, 'deferred_tx_counter': 64.0, 'entity_id': 260.0, 'excessive_collision_counter': 24.0, 'frames_too_long': 4.0, 'internal_mac_tx_error_counter': 27.0, 'interval_end_time': 0.0, 'late_collision_counter': 68.0, 'multiple_collisions_frame_counter': 20.0, 'single_collision_frame_counter': 27.0, 'sqe_counter': 17.0}

4. Missing buffer_overflows_on_rx in metrics:

'metrics':

{'alignment_error_counter': 56.0, 'buffer_overflows_on_tx': 24.0, 'carrier_sense_error_counter': 57.0, 'class_id': 24.0, 'deferred_tx_counter': 48.0, 'entity_id': 257.0, 'excessive_collision_counter': 0.0, 'fcs_errors': 99.0, 'frames_too_long': 29.0, 'internal_mac_rx_error_counter': 46.0, 'internal_mac_tx_error_counter': 72.0, 'interval_end_time': 0.0, 'late_collision_counter': 16.0, 'multiple_collisions_frame_counter': 3.0, 'single_collision_frame_counter': 20.0, 'sqe_counter': 89.0}