(fix, go): Required properties don't specify omitempty

[amckinney]

Overview

This fixes an issue where required properties are omitted in the type's wire representation. This feature is gated behind a feature flag to preserve the behavior found in current SDKs.

When alwaysSendRequiredProperties is enabled, required properties are never omitted in the type's wire representation. Any required property that is not explicitly set will send the default value for that type. The configuration to enable this behavior is shown below:

- name: fernapi/fern-go-sdk
  version: 0.23.0
  config:
    alwaysSendRequiredProperties: true

Example

Consider the following types:

type CreateUserRequest struct {
  Admin   *User   `json:"admin"`
  Members []*User `json:"members"`
}

type User struct {
  Name string `json:"name"`
}

If the CreateUserRequest is constructed without any values, it will send null for both fields. If it is instead constructed with the zero value of the underlying type, the empty representation will be sent:

// The following is serialized as `{"admin": null, "members": null}`
nullRequest := &CreateUserRequest{}

// The following is serialized as `{"admin": null, "members": []}`
noMembersRequest := &CreateUserRequest{
  Members: []*User{},
}

// The following is serialized as `{"admin":{"name":""}, "members":[]}`
emptyValueUserRequest := &CreateUserRequest{
  Admin:   &User{},
  Members: []*User{},
}

// The following is serialized as `{"admin":{"name": "john.doe"}, "members":[{"name": "jane.doe"}]}`
simpleUserRequest := &CreateUserRequest{
  Admin:   &User{
     Name: "john.doe",
  },
  Members: []*User{
    {
      Name: "jane.doe",
    },
  },
}