Constant CREATE_ISSUE 

pub const CREATE_ISSUE: &str = r#"mutation($input:CreateIssueInput!){createIssue(input:$input){issue{id number url}}}"#;

Creates one issue. Outside a copy it is created on no board, and ADD_TO_BOARD files it; inside one, its input names the board in projectV2Ids and its project in parentIssueId, so this one request files it under both — see GitHubProjectsSource::create_filed_issue.