How to get all the properties of a target

In CMake, I want to get all property names that are set for a target.

In this post(How to print all the properties of a target in cmake? - Stack Overflow), they use cmake --help-property-list to list a predefined set.
But if you have a target that defines other properties how can I know which are they?
For example

set_target_properties(some_target PROPERTIES some_custom_property prop_val)

How can I get all such properties? I am looking for something like:


Or print all properties and they values

There does not seem to be a CMake-language exposure of this. A feature request would be appropriate though.