According to @delagoya we need to change this ASAP:

I don't know who needs to hear this, but:

If you use AWS Batch, you should default to using the new ecsProperties parameter for all your job definitions. Migrate any past job definition to a new version that moves from containerProperties

Otherwise you are going to Experience Bij later when you have to submit jobs with overrides and forget where in the API those overrides go, depending on the job definition

See also: #4979 where this was a requirement for supporting ipcMode.

NB also the proposed move to Java SDKv2 (#4741), though this shouldn't be required for this switch according to #4979 (comment)