What is GraphQL proxy support in Apigee?

<!-- GraphQL policy: validate and protect GraphQL requests -->
<GraphQL name="GQL.Validate">
  <Action>parse</Action>
  <!-- Reference the uploaded GraphQL schema -->
  <ResourceURL>graphql://schema.graphql</ResourceURL>
  <!-- Protect against deeply nested queries -->
  <MaxDepth>10</MaxDepth>
  <!-- Limit number of fields per query to prevent data scraping -->
  <MaxCount>100</MaxCount>
</GraphQL>

<!-- Supported operations:
  parse     - validates the GraphQL query syntax and schema compliance
  verify    - validates that the operation is in the schema

  The policy catches:
  - Malformed GraphQL syntax
  - Operations not in the schema
  - Queries exceeding MaxDepth (circular/deep nesting attacks)
  - Queries exceeding MaxCount (field count explosion) -->

<!-- Typical proxy structure for GraphQL:
  Client -> POST /graphql (query in body)
  ProxyEndpoint:
    PreFlow:
      - VerifyAPIKey  (or OAuthV2 VerifyToken)
      - SpikeArrest
      - GQL.Validate  <- GraphQL-specific validation
  TargetEndpoint -> GraphQL backend service

  Note: Apigee proxies GraphQL as HTTP POST -
  standard HTTP policies (auth, rate limiting) all apply normally -->