Javadoc
By default, the ConditionType of a Sequence Flow is None. This means that there is no evaluation at runtime to
determine whether or not the Sequence Flow will be used. Once a Token is ready to traverse the Sequence Flow (i.e.,
the Source is an activity that has completed), then the Token will do so. The normal, uncontrolled use of Sequence
Flow, in a sequence of activities, will have a None ConditionType. A None ConditionType MUST NOT be used if the
Source of the Sequence Flow is an Exclusive Data-Based or Inclusive Gateway. The ConditionType attribute MAY be set
to Expression if the Source of the Sequence Flow is a Task, a Sub-Process, or a Gateway of type Exclusive-Data-
Based or Inclusive. If the ConditionType attribute is set to Expression, then a condition marker SHALL be added to
the line if the Sequence Flow is outgoing from an activity. However, a condition indicator MUST NOT be added to the
line if the Sequence Flow is outgoing from a Gateway. An Expression ConditionType MUST NOT be used if the Source of
the Sequence Flow is an Event-Based Exclusive Gateway, a Complex Gateway, a Parallel Gateway, a Start Event, or an
Intermediate Event. In addition, an Expression ConditionType MUST NOT be used if the Sequence Flow is associated
with the Default Gate of a Gateway. The ConditionType attribute MAY be set to Default only if the Source of the
Sequence Flow is an activity or an Exclusive Data-Based Gateway.