presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/CassandraMetadata.java/CassandraMetadata/getColumnHandles
class CassandraMetadata:    @Override
    public Map<String, ColumnHandle> getColumnHandles(ConnectorSession session, ConnectorTableHandle tableHandle)
    {
        requireNonNull(session, "session is null");
        requireNonNull(tableHandle, "tableHandle is null");
        CassandraTable table = cassandraSession.getTable(getTableName(tableHandle));
        ImmutableMap.Builder<String, ColumnHandle> columnHandles = ImmutableMap.builder();
        for (CassandraColumnHandle columnHandle : table.getColumns()) {
            columnHandles.put(CassandraCqlUtils.cqlNameToSqlName(columnHandle.getName()).toLowerCase(ENGLISH), columnHandle);
        }
        return columnHandles.build();
    }