MapWtf.groovy

import groovy.transform.*

@CompileStatic
Map<String, ?> makeMap() {
  def map = [string: "string"]
  map.number = 1
  return map
}

def map = makeMap()
map.each { println it.value.getClass().name }

This is weird. I have also noticed it works for initialization like below:

def map = [string: 'string', numbers: [1, 2, 3, 4].collect { [n: it] } ]

println map.number.getClass().name

immediately after line 6 prints as String.