Enhance Tradista Business objects implementation

[oasuncion]

Whatever the business object is in Tradista, the following rule seems to be always verified:

For 2 objects:

• if both have positive ids they are equal if their ids are equal otherwise they are different
• otherwise they are equal if they have the same business key. The business key is one or several of the object fields (ex: ISO code for a currency).

Analyse and confirm that the below statement is correct for all objects. In such case, think about a generic implementation of the equals and hashcode methods, with usage of an abstract businessKey method that will be implemented by any Tradista object.

Such change will ease the maintenance of the application, we will have reliable equals/hashcode methods that will help in many situations.

[oasuncion]

equals method of TradistaObject is now implemented as follows:

• if both objects have positive ids they are equal if their ids are equal otherwise they are different
• otherwise they are equal if they have the same business key. The business key is one or several of the object fields (ex: ISO code for a currency).

hashcode method of TradistaObject is now implemented as follows: hashcode is calculated using fields of the composite key. If the object doesn't have a composite key, hashcode implementation of Object class is used.

Fields of a TradistaObject that are part of the business key must be annotated "Id".

In addition, on this ticket, TradistaObject class has been made Cloneable and clone() method of TradistaObjects have been implemented so only deep copies of mutable attributes are part of the clone. Also, getters of mutable attributes provide deep copies of them.