List existing cluster's constraints.

The cluster constraints endpoint returns a list of active (non-expired) constraints that apply to a cluster.
Constraints can consist in:

• operational ranges, i.e min/max ranges within which the DER can be operated with. These therefore correspond to inequality constraints. For example, to allow a battery to only discharge up to 2kW, set maxActivePower=0 and minActivePower=-2000.
  To limit the power output of an inverter to 7kW, set minActivePower=-7000.

• direct set points, i.e. the control value directly expected to be applied to an appliance. These therefore correspond to equality constraints. For example, to charge an EV with 2kW, set activePower = 2000.

To each constraint is associated:

• a date after which the constraint expires (invalidAt)

• a priority level: 0-low, 2^31-1(2147483647)-high.

Constraints can also originate from appliances:

• the physical operation limits of the appliance are always associated to the highest priority level (2^31-1).

• a local-user specific input may also trigger additional constraints. For example, if the manager of an EV fleet would like the fleet to charge only with PV surplus, but the car owner needs his car to charge faster, there might be conflicting constraints.

  The priority of each constraint will therefore also depend on the priority associated to the emitter of the constraint.