ReadOnlyCall errors when omitting optional parameters.

[edatts]

Hello, I was attempting to make a read only smart contract call to the Dusa Factory Contract on Buildnet using the gRPC APIs and ran into an error.

What happened:

I executed a read only call on a contract without specifying a caller address and received an error:

rpc error: code = Internal desc = Runtime error: spending address <RANDOM_ADDRESS> not found

I executed a read only call on a contract without specifying a fee and received an error:

rpc error: code = InvalidArgument desc = fee is too low provided: 0 , minimal_fees required: 0.01

What I expected:

The following comments mark the Address and Fee fields as optional so I expected that I could make a read-only contract call without specifying an address or a fee.

massa-proto/proto/commons/massa/model/v1/execution.proto

Line 390 in 20972cd

// Caller's address, (Optional) if not set, an auto-generated address will be used

massa-proto/proto/commons/massa/model/v1/execution.proto

Line 392 in 20972cd

// fee paid by the caller when the call is processed (optional)

Since read-only calls do not change the state of the contract or ledger I am not sure why I cannot make a read only call with addresses that do not yet have associated datastore entries or without specifying a fee?