This function is the lower-level function that powers the API call: it takes a URL and headers and executes the http request with rate-limiting and authentication. It checks for JSON return and any warnings/errors, parses the json, and returns an espn_api object with the parsed content, the raw response, and the actual query.
espn_getendpoint_raw(conn, url_query, ...)
a connection object created by ff_connect or equivalent - used for authentication
a fully-formed URL to call
any headers or other httr request objects to pass along
object of class espn_api with parsed content, request, and response