* Returns the file object for the given location and linkage or {@code null} if the file
	 * was not indexed in this linkage.
	 * <p>
	 * When a header file is stored in the index in multiple variants for different sets of macro
	 * definitions, this method will return an arbitrary one of these variants.
* Returns the file object for the given location and linkage or {@code null} if the file
	 * was not indexed in this linkage.
	 * <p>
	 * When a header file is stored in the index in multiple variants for different sets of macro
	 * definitions, this method will return an arbitrary one of these variants. | IIndex.java