/**
 * @module nullToEmpty
 * @description Returns the specified value if non-null, otherwise an empty array.
 * @param {Object} input - The object to investigate
 * @returns Object - The specified value if non-null, otherwise an empty array
 * @example {{ readField('jvm', 'files') | nullToEmpty }}
 */
function nullToEmpty(input) {
    let output;
    if (input) {
        output = input;
    } else {
        output = [];
    }

/**
 * @module byCodeowner
 * @description Groups the PR's files' by owner based on the CODEOWNERs file.
 * @param {string[]} files - the gitStream's files context variable
 * @param {Object} pr - the gitStream's pr context variable
 * @param {string} token - access token with repo:read scope, used to read the CODEOWNERS file
 * @param {string} pathToCodeOwners - path from repo root to CODEOWNERS file
 * @returns {Map} - Map from owner name to list of files they own