How can I configure a Map type attribute to be projected as a NonKeyAttribute for a Global Secondary Index?

Basically need configure a DynamoDB table with a Global Secondary Index that projects a Map type attribute. Would this configuration work?

Resources:
DynamoDbTable:
  Type: 'AWS::DynamoDB::Table'
  DeletionPolicy: Retain
  Properties:
    AttributeDefinitions:
      - AttributeName: email_id
        AttributeType: S
      - AttributeName: user_id
        AttributeType: N
      - AttributeName: metrics
        AttributeType: M
    KeySchema:
      - AttributeName: email_id
        KeyType: HASH
    ProvisionedThroughput:
      ReadCapacityUnits: 50
      WriteCapacityUnits: 5
    TableName: ${self:custom.dynamoDBTable}
    GlobalSecondaryIndexes:
    - IndexName: user_id-index
      KeySchema:
      - AttributeName: user_id
        KeyType: HASH
      Projection:
        ProjectionType: INCLUDE
        NonKeyAttributes:
        - metrics
      ProvisionedThroughput:
        ReadCapacityUnits: 50
        WriteCapacityUnits: 5