Mismatch in Docker Field Names for timeNano and Other Fields Using --format '{{json.timeNano}}'

• This is a bug report
• This is a feature request
• I searched existing issues before opening this one

Expected behavior

The JSON output the field names should be able to be used directly vs changing the the field name to start with uppercase
docker system events --since 1h --until 1m --format '{{json .}}'

This should work as it matches the JSON field name.
docker system events --since 1h --until 1m --format '{{json .timeNano}}'

Actual behavior

// This does not work and generates an error -- timeNano
docker system events --since 1h --until 1m --format '{{json .timeNano}}'

// This works -- TimeNano
docker system events --since 1h --until 1m --format '{{json .TimeNano}}'

Steps to reproduce the behavior

Docker version 20.10.8, build 3967b7d
Ubuntu: 18.04.5 LTS

Running this command outputs JSON as expected.
docker system events --since 1h --until 1m --format '{{json .}}'

Inside of the JSON data will find the field timeNano is output in JSON like below:
"timeNano":1631794341804708170

However, running the command below results in an error. If "TimeNano" is used instead it works to show the data.
docker system events --since 1h --until 1m --format '{{json .timeNano}}'

Results in an error below:
Error parsing format: template: :1:7: executing "" at <.timeNano>: can't evaluate field timeNano in type *eventsMessage

There is a mismatch in additional field names for roughly 30% of the field names have issues similar to above due to the field name not matching due to case sensitivity and inconsistency.

Output of docker version:

Docker version 20.10.8, build 3967b7d

Output of docker info:

Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Build with BuildKit (Docker Inc., v0.6.1-docker)
  scan: Docker Scan (Docker Inc., v0.8.0)

Server:
 Containers: 14
  Running: 9
  Paused: 0
  Stopped: 5
 Images: 274
 Server Version: 20.10.8
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: e25210fe30a0a703442421b0f60afac609f950a3
 runc version: v1.0.1-0-g4144b63
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: default
 Kernel Version: 5.4.0-84-generic
 Operating System: Ubuntu 18.04.5 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 8
 Total Memory: 15.56GiB
 Name: eia-NUC8i7HVK
 ID: A2MN:75RO:IDNC:VXXS:QIXL:S6KB:C5E3:CSSJ:S2NV:ZOR4:DOBS:DFFT
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: No swap limit support

Additional environment details (AWS, VirtualBox, physical, etc.)

Start by reproducing the Docker CLI system events commands with --format '{{json .}}' and the .timeNano and .TimeNano variants. Trace the system events format handling to determine why JSON field names differ from template field names; done means the documented lowercase field names work consistently, including timeNano.