Is 'id' a reserved property name for Neo OGM?

I found this statement from February 2018 in a Neo OGM Github issue:

If you want to use custom ids the attribute should have a @GeneratedValue annotation. Additional keep in mind that the name id is reserved for OGM internal id handling. Please use another name for the attribute.

Is this still true (or even was it ever true)? Is there any documentation regarding this?

This statement is not true anymore. You can name the variable also to id and use it as a custom id field.