Returns the unique identifier assigned by the system upon session creation.
<p/>
All return values from this method are expected to have proper {@code toString()},
{@code equals()}, and {@code hashCode()} implementations. Good candidates for such
an identifier are {@link java.util.UUID UUID}s, {@link java.lang.Integer Integer}s, and
{@link java.lang.string string}s.
@return The unique identifier assigned to the session upon creation.
Returns the unique identifier assigned by the system upon session creation. <p/> All return values from this method are expected to have proper {@code toString()}, {@code equals()}, and {@code hashCode()} implementations. Good candidates for such an identifier are {@link java.util.UUID UUID}s, {@link java.lang.Integer Integer}s, and {@link java.lang.string string}s.
@return The unique identifier assigned to the session upon creation.