Adds a metadata to a task
Task ID
The name of the calling system passed along as a header parameter
If metadata is for system or customer, isSystem = true is only of ProjectManager
If false we merge with the keys
Customer or system metadata
Success
If the API call failed, this will contain information about the error that occurred.
True if the API call succeeded; false otherwise.
True if the API call failed.
The HTTP code of the response.