.accepts("schema-file", "File containing schema, must not occur with inline schema.")
.withOptionalArg()
.ofType(String.class);
OptionSet optionSet = optionParser.parse(args.toArray(new String[0]));
List<String> nargs = (List<String>)optionSet.nonOptionArguments();
String schemaFile = schemaFileOption.value(optionSet);
if (nargs.size() != (schemaFile == null ? 2 : 1)) {
err.println("jsontofrag --schema-file <file> [inline-schema] input-file");
err.println(" converts JSON to Avro fragments.");