Retrieves every key inside hash_table, as an array.
The returned array is NULL-terminated but may contain NULL as a key. Use length to determine the true length if it's possible that NULL was used as the value for a key.
Note: in the common case of a string-keyed glib.HashTable, the return value of this function can be conveniently cast to (const gchar **).
You should always free the return result with g_free(). In the above-mentioned case of a string-keyed hash table, it may be appropriate to use g_strfreev() if you call HashTable.stealAll first to transfer ownership of the keys.