AI-generated Key Takeaways
- 
          This page describes operations on a custom interest, specifically creation and update. 
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          The update_maskfield is used to specify which resource fields are modified during an update operation.
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          The operationfield can be eithercreatefor a new custom interest orupdatefor an existing custom interest with a valid resource name.
A single operation (create, update) on a custom interest.
| Fields | |
|---|---|
| 
 | FieldMask that determines which resource fields are modified in an update. | 
| Union field 
 | |
| 
 | Create operation: No resource name is expected for the new custom interest. | 
| 
 | Update operation: The custom interest is expected to have a valid resource name. |