presto-rcfile/src/main/java/io/prestosql/rcfile/RcFileWriter.java/RcFileWriter/writeMetadataProperty
class RcFileWriter:    private void writeMetadataProperty(String key, String value)
    {
        writeLengthPrefixedString(output, utf8Slice(key));
        writeLengthPrefixedString(output, utf8Slice(value));
        recordValidation(validation -> validation.addMetadataProperty(key, value));
    }