Error defining relationships implementing interfaces in GraphQL Library

Hi,

Using following definitions:

interface IGraphEdge @relationshipProperties {

created: DateTime! @timestamp(operations: \[CREATE\])  

modified: DateTime! @timestamp(operations: \[CREATE, UPDATE\])  

}

interface IPerson {

displayName: String!  

knows: \[IPerson!\]! @relationship(type: "KNOWS", direction: OUT, properties: "IGraphEdge")  

}

type Employee implements IPerson {

displayName: String!  

knows: \[IPerson!\]! @relationship(type: "KNOWS", direction: OUT, properties: "IGraphEdge")  

}

type Contractor implements IPerson {

displayName: String!  

knows: \[IPerson!\]! @relationship(type: "KNOWS", direction: OUT, properties: "IGraphEdge")  

}

Yields the following error:

Error: Input Object type IGraphEdgeCreateInput must define one or more fields.

Input Object type IGraphEdgeUpdateInput must define one or more fields.

Adding a field to the IGraphEdge resolves the issue but is not required - I only require the created and modified date times on my basic edges.

interface IGraphEdge @relationshipProperties {

created: DateTime! @timestamp(operations: \[CREATE\])  

modified: DateTime! @timestamp(operations: \[CREATE, UPDATE\])  

creator: String!  

modifier: String!  

}

What am I missing here?