private void expect(JsonToken token) throws IOException {
            if (parser.nextToken() != token)
                throw new OperationParseException("Expected '" + token + "' at offset " + parser.currentTokenLocation().getByteOffset() +
                        ", but found '" + parser.currentToken() + "' (" + parser.getText() + ")");
        }
Same as {@link #feedMany(InputStream, ResultCallback)}, but without a provided {@link ResultCallback} instance.
@see JsonFeeder#feedMany(InputStream, ResultCallback) for details.
vespa-feed-client-api/src/main/java/ai/vespa/feed/client/JsonFeeder.java