Properties block affects property while it's condition is false

I try to set module property under some condition using Properties block. When blocks condition is false this property changes its value and becomes undefined.

Here is minimal example targeting Android:

Project {
    CppApplication {
        Properties {
            condition: false
            cpp.syslibroot: "anything"//if i comment this line cpp.syslibroot has valid path
        }
    }
}

In this example cpp.syslibroot becomes undefined when i try to use it in Properties block (condition is always false).

why property cpp.syslibroot is affected such way?