old_contents: import { assert } from '@ember/debug';
  
  export function buildOperationUrl(record, opPath, urlType, instance = true) {
    assert('You must provide a path for instanceOp', opPath);
    let modelName = record.constructor.modelName || record.constructor.typeKey;
    let adapter = record.store.adapterFor(modelName);
    let path = opPath;
    let snapshot = record._createSnapshot();
    let baseUrl = adapter.buildURL(modelName, instance ? record.get('id') : null, snapshot, urlType);
  
    if (baseUrl.charAt(baseUrl.length - 1) === '/') {
      return `${baseUrl}${path}`;
    } else {
      return `${baseUrl}/${path}`;
    }
  }
  
  export default buildOperationUrl;
  
new_contents: export function buildOperationUrl(record, opPath, urlType, instance = true) {
    let modelName = record.constructor.modelName || record.constructor.typeKey;
    let adapter = record.store.adapterFor(modelName);
    let path = opPath;
    let snapshot = record._createSnapshot();
    let baseUrl = adapter.buildURL(modelName, instance ? record.get('id') : null, snapshot, urlType);
  
    if (!path) {
      return baseUrl;
    }
    
    if (baseUrl.charAt(baseUrl.length - 1) === '/') {
      return `${baseUrl}${path}`;
    } else {
      return `${baseUrl}/${path}`;
    }
  }
  
  export default buildOperationUrl;
  
subject: Allow empty paths