Fix types

[bettio]

Some of the internal APIs have suboptimal types or have typing inconsistencies. E.g. int used for booleans instead of bool.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later