protected void ensureRowKey(E key) {
		if (!rowKeys.containsKey(key)) {
			rowKeys.put(key, rowKeys.size());
			addRow();
		}
	}
protected void ensureRowKey ( E key ) { if ( ! rowKeys . containsKey ( key ) ) { rowKeys . put ( key , rowKeys . size ( ) ) ; addRow ( ) ; } }
Checks if the given row-key is already known and optionally generates a new key mapping.<br>
@param key Row-value of indexing type