keepMapValues: true merge option is not considered with CombineFromComposite patch when transforming json string to object

[fcke]

Problem statement

The keepMapValues: true merge option does not have effect when it is used in a CombineFromComposite patch along with the transforms operation.

What happened?

I have the following patch:

   - type: CombineFromComposite
     combine:
       strategy: string
       string:
         fmt: '{"%s-%s":{"url":"http://%s.4.48:8080","tls":"DISABLE","tlsSecret":null,"protocol":"h2c"}}'
       variables:
         - fromFieldPath: spec.parameters.valueString1
         - fromFieldPath: spec.parameters.valueString2
         - fromFieldPath: spec.parameters.baseCidrOctets
     toFieldPath: spec.forProvider.manifest.spec.values.chartValues.global.externalServices
     policy:
       mergeOptions:
         keepMapValues: true
     transforms:
     - type: convert
       convert:
         toType: object
         format: json 

The patch works fine when I do not have anything under spec.forProvider.manifest.spec.values.chartValues.global.externalServices. However, when there is already an existing sub-tree, it is overwritten with the newly created json-transformed-to-object value despite of the keepMapValues: true merge option.

Resource, before patch:

  externalServices:
     zService:
       ip: zservice.svc.cluster.local
       ports:
         cm: 8080
         fm_alarm: 8079
         fm_log: 8078
         pm: 8079

After patch:

  externalServices:
     valueString1-valueString2:
       ip: 1.2.4.48:8080
       tls: DISABLE
       tlsSecret: null
       protocol: h2c

However, when I have two separate patch, one for the combine and another one for the transform, the keepMapValues: true has the expected effect and the newly created object is merged.
So, when I have the following patch added to another resource, just to create the proper string which I can use in the original resource for patching (really ugly, but do not know any better way currently...):

  - type: CombineFromComposite
    combine:
      strategy: string
      string:
        fmt: '{"%s-%s":{"url":"http://%s.4.48:8080","tls":"DISABLE","tlsSecret":null,"protocol":"h2c"}}'
      variables:
         - fromFieldPath: spec.parameters.valueString1
         - fromFieldPath: spec.parameters.valueString2
         - fromFieldPath: spec.parameters.baseCidrOctets
    toFieldPath: metadata.annotations.externalServiceNew
  - type: ToCompositeFieldPath
    fromFieldPath: metadata.annotations.externalServiceNew
    toFieldPath: metadata.annotations.externalServiceNew

And I use the transform to patch the target resource (note: fromFieldPath: Required is there to prevent creation of the resource before the formatted string is available as I need the changes to the externalServices when this resource is created):

  - type: FromCompositeFieldPath
    fromFieldPath: metadata.annotations.externalServiceNrf
    toFieldPath: spec.forProvider.manifest.spec.values.chartValues.global.externalServices
    policy:
      fromFieldPath: Required
      mergeOptions:
        keepMapValues: true
    transforms:
    - type: convert
      convert:
        toType: object
        format: json

Everything works flawlessly.

Example:
Resource, before patch:

  externalServices:
    zService:
      ip: zservice.svc.cluster.local
        ports:
          cm: 8080
          fm_alarm: 8079
          fm_log: 8078
          pm: 8079

After patch:

  externalServices:
     valueString1-valueString2:
       ip: 1.2.4.48:8080
       tls: DISABLE
       tlsSecret: null
       protocol: h2c
     zService:
       ip: zservice.svc.cluster.local
       ports:
         cm: 8080
         fm_alarm: 8079
         fm_log: 8078
         pm: 8079

What environment did it happen in?

Crossplane version: 1.15.0
Cloud provider: AWS EKS
Kuberetes: 1.29

[fcke]

ping :)