Problem

ECS hotswap fails on a task definition containing log configuration like the following.

const taskDefinition = new ecs.FargateTaskDefinition(stack, 'Task', {});

taskDefinition.addContainer('EcsApp', {
  image: ecs.ContainerImage.fromRegistry('nginx:stable'),
  logging: ecs.LogDriver.awsLogs({ streamPrefix: 'log' }),
});

Root cause

When we transform object keys in a task definition, we pass excludeFromTransform to avoid from transforming keys with arbitrary string, such as logDriver.options.

However, it was not working when we transform keys with upperCaseFirstCharacter, because the keys in excludeFromTransform was uppercased, where the source object was lowercased.

// source task definition
{
  "logConfiguration": {
      "logDriver": "awslogs",
      "options": {
          "awslogs-group": "my-test-stack-TaskEcsAppLogGroupD5C9C1DD-BPB6zgX4S0wU",
          "awslogs-region": "ap-northeast-1",
      },
  },
}

// excludeFromTransform 
{ 
  LogConfiguration: {
      Options: true,
    },
  },
}

// where it should be
{ 
  logConfiguration: {
      options: true,
    },
  },
}

This misconfiguration resulted in the output task definition uppercased in an unexpected way:

{
  "logConfiguration": {
      "logDriver": "awslogs",
      "options": {
          "Awslogs-group": "my-test-stack-TaskEcsAppLogGroupD5C9C1DD-BPB6zgX4S0wU",
          "Awslogs-region": "ap-northeast-1",
      },
  },
}

The problem was not detected by unit tests because they only contained cases with uppercase keys in a source task definition.

Fix

Use lowercased excludeFromTransform when we use it with upperCaseFirstCharacter, also adding a test case with lowercased keys in a source task definition.

Closes #26871.

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