Add needed includes and remove uneeded includes. Task-number: QTBUG-117425 Pick-to: 6.5 Change-Id: Iec4cc7a862aa164742e502f33447fa939dfb53ae Reviewed-by: Ivan Solovev <ivan.solovev@qt.io> (cherry picked from commit 9ed067e719346f91a2f4a0e50efefe333e00d5af) Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
Qt is supplied with a number of example applications that have been written to provide developers with examples of the Qt API in use, highlight good programming practice, and showcase features found in each of Qt's core technologies. Documentation for examples can be found in the Examples section of the Qt documentation.