public static boolean isNullable(ColumnMetaData metaData) {
        switch (metaData.getNullable()) {
            case DatabaseMetaData.columnNullable:
            case DatabaseMetaData.columnNullableUnknown: return true;
            case DatabaseMetaData.columnNoNulls: return false;
            default: throw new SpeedmentException(
                "Unknown nullable type " + metaData.getNullable());
        }
    }
Code returns {@code true} if the column with the specified metadata can
sometimes hold {@code NULL}-values in the database, otherwise
{@code false}.

@param metaData  the metadata object retrieved from JDBC
@return  {@code true} if nullable, else {@code false}
runtime-parent/runtime-connector-parent/sqlite/src/main/java/com/speedment/runtime/connector/sqlite/internal/util/MetaDataUtil.java