How to use broccoli-concat - 1 common examples

// something went really wrong, open an issue
          throw new Error('Embroider: EWUT');
        } else if (headerFiles.length === 1) {
          // app.import(x, { outputFile: y }); where only one app.imports had this outputFile
          //
          // No concat needed. Simply serialize the remapping in the addon's
          // manifest, this ensures it is included in the final output with no extra work.
          this._publicAssets[headerFiles[0]] = importPath;
        } else {
          // app.import(x, { outputFile: y }); where multiple app.imports share one outputFile
          // Concat needed. Perform concat, and include the outputFile in the
          // addon's manifest. This ensures it is included in the final output
          this._publicAssets[importPath] = importPath;

          concatentations.push(
            new Concat(tree, {
              headerFiles,
              outputFile: importPath,
              annotation: `Package ${importPath}`,
              separator: '\n;',
              sourceMapConfig: this.app.options['sourcemaps'],
            })
          );
        }
      }
    }

    this.addOtherAssets();
    return mergeTrees([tree, ...concatentations], { overwrite: true });
  }