public static void copy(Reader reader, Writer writer, char[] buf) throws IOException {
		int r;
		while ((r = reader.read(buf)) != -1) {
			writer.write(buf, 0, r);
		}
	}
Transfers content of {@link Reader} into {@link Writer}.

@param reader
		Reader to transfer content from.
@param writer
		Writer to transfer content to.
@param buf
		Buffer that is used to hold data.

@throws IOException
		When any I/O error occurs.
recaf-core/src/main/java/software/coley/recaf/util/IOUtil.java