Unable to specify variable type in environment variables override

When I try to pass in a name value pair in environment variables, the type gets set to PLAINTEXT even though the type in the job was set to SECRETS_MANAGER. I'd like to be able to specify the type of the variable during the start build envVariables override. This is how it already works on the AWS CLI:

CodeBuild environment variable keys and values cannot be empty and the string must be of the form [{key, value}, {key2, value2}] (Service: null; Status Code: 0; Error Code: null; Request ID: null; Proxy: null

Start at the Jenkins build step's start-build envVariables override handling and compare its accepted environment-variable shape with the AWS CLI syntax shown in the issue. Done means an override can specify a variable type and preserve SECRETS_MANAGER instead of forcing PLAINTEXT, while retaining validation for non-empty keys and values.

Written by the indexing model from the issue text.