void addIndex(IndexTable indexTable) {
		secondaryIndexes.put(indexTable.getColumnIndex(), indexTable);
		indexedColumns = secondaryIndexes.getKeys();
		isIndexed = true;
	}
Add an existing secondary index.
NOTE: Records for this table instance must not be modified until
after all existing secondary indexes are added.  Failure to comply may
result in an inconsistent index.
@param indexTable secondary index table
Ghidra/Framework/DB/src/main/java/db/Table.java