presto-spi/src/main/java/io/prestosql/spi/block/SingleMapBlock.java/SingleMapBlock/checkNotIndeterminate
class SingleMapBlock:    private static void checkNotIndeterminate(Boolean equalsResult)
    {
        if (equalsResult == null) {
            throw new PrestoException(NOT_SUPPORTED, "map key cannot be null or contain nulls");
        }
    }