public DWARFLineContentType getId() {
			return super.getAttributeId();
		}
Reads a {@link DWARFLineContentType.Def} instance from the {@link BinaryReader reader}.
<p>
Returns a null if its a end-of-list marker.

@param reader {@link BinaryReader} stream
@return {@link DWARFLineContentType.Def}, or null if stream was at a end-of-list marker
(which isn't really a thing for line content defs, but is a thing for attribute defs)
@throws IOException if error reading
Ghidra/Features/Base/src/main/java/ghidra/app/util/bin/format/dwarf/line/DWARFLineContentType.java