FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
In the class com.sun.javafx.binding.MapExpressionHelper's inner class SimpleChange's toString() method, the message generated is missing a space character in the case where a put operation has been performed (addOp==true && removeOp==true). The first part of the message is generated with this code which does not add a space character before "by":

builder.append("replaced ").append(old).append("by ").append(added);


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
javafx.beans.property.MapProperty<String,String> mp = new javafx.beans.property.SimpleMapProperty<>(javafx.collections.FXCollections.observableHashMap());
mp.addListener(new javafx.collections.MapChangeListener<String, String>(){
@Override
public void onChanged(
javafx.collections.MapChangeListener.Change<? extends String, ? extends String> change) {
System.out.println(change);
}}
);
mp.put("a", "b");
mp.put("a", "c");
---------- END SOURCE ----------