curl \
    -X POST \
    -H "Content-Type: application/json" \
    --data '{"query":"  mutation createRepresentation ($input: CreateRepresentationInput!) {    createRepresentation (input: $input) {      __typename      ... on ErrorPayload {        message      }    }  }","variables":{"input":{"id":"5eab377a-cfa0-4d3e-b6f6-38d5190e05cf","objectId":"5d99c844-a3b4-4723-932f-6285cd116275","editingContextId":"7f9f322f-8767-40ce-8bcf-4f3b44e9bcda","representationDescriptionId":"5eab377a-cfa0-4d3e-b6f6-38d5190e05cf","representationName":"TestRepresentation"}}}' \
    http://localhost:8080/api/graphql

'No handler found for event: CreateRepresentationInput {id: 5eab377a-cfa0-4d3e-b6f6-38d5190e05cf, editingContextId: 7f9f322f-8767-40ce-8bcf-4f3b44e9bcda, representationDescriptionId: 5eab377a-cfa0-4d3e-b6f6-38d5190e05cf, objectId: 5d99c844-a3b4-4723-932f-6285cd116275, representationName: TestRepresentation}

I inserted the current editingContextId and the objectId (which I assume correlates to the documentId?). The id and representationDescriptionId are set randomly.

• The "editingContextId" is not the documentId but the projectId (in most cases, you can assume editingContext == project).
  
• The "objectId" should be the id of the semantic element on which the new representation is to be created
  
• The plain "id" can be randomly chosen, it only serves as an identifier for the request itself
  
• The "representationDescriptionId" is *not* random, it should be the id of the type of representation you want to create, typically a DiagramDescription.