Default argument value in function documentation

Consider the following documentation for a function f1 in a module CGP

"""
$(TYPEDSIGNATURES)
"""
function f1(a::Int, b::Int=0)
    return a + b
end

The generated documentation is

Two signatures are produced, but information of the default value is lost. I have to document the default value of b manually.

Is it possible to produce a single signature that contains the default value? Something like follows

f1(a::Int64, b::Int64=0) -> Int64

Reproduce the documented f1(a::Int, b::Int=0) example in module CGP and inspect how TYPEDSIGNATURES generates its two signatures. Compare the generated output with the requested single signature containing b=0; done means default values are preserved without manual documentation, with existing documentation behavior still working.