A Dynamic Action on the Country select list uses the APEX CLOB Load 2 plugin to load the geometry for the country's borders into the hidden P22_GEOJSON item.
A Dynamic Action on P22_GEOJSON runs the JK64 Report Google Map R1 Action action "loadGeoJsonString", with the value based on the following JavaScript expression:
'{"type":"Feature","geometry":'+$v("P22_GEOJSON")+',"properties":{"name":"'+$v("P22_COUNTRY")+'"}}'
Alternatively, to load GeoJSON onto the map programmatically, the following Javascript API call may instead be used:
$("#map_testmap").reportmap("loadGeoJsonString", '...your geoJON here...');
Even better, you can load GeoJSON onto the map via the SQL Query.