GCP APIGateway Custom authorizer

Hi ,

We are planning to integrate GCP APIGateway in our project. I am started exploring the APIGateway, seems like there is no custom authorizer support like aws, can you please guide how to add authorizer for gcp as well.Can you please help me here to understand more on this.

Ex: for aws

• securityDefinitions:
• APIGatewayAuthorizer:
• type: apiKey
• name: Authorization
• in: header
• x-amazon-apigateway-authtype: oauth2
• x-amazon-apigateway-authorizer:
• type: token
• authorizerUri: arn:aws:apigateway:us-east-1:lambda:path/2015-03-31/functions/arn:aws:lambda:us-east-1:account-id:function:function-name/invocations
• authorizerCredentials: arn:aws:iam::account-id:role
• identityValidationExpression: "^x-[a-z]+"
• authorizerResultTtlInSeconds: 60