Properties entity in Bonita v3 has been renamed to Variables in Bonita v4. This seems a more natural way to work with workflow relevant data.
Variables support and flexibility in Bonita v3 was too limited. Only String and enumerated types were supported. In Bonita v4 support for common variables types as well as as advanced ones (including own Java based ones) will be added in next RC (currently, the RC2 version support same types than v3).
Getting and Setting variables operations directly handles Java Objects, meaning that a get operation returns an Object so the developer only needs to use the instanceOf operator to determine the type of a particular variable.