energyCapacity property
IF not null, this plug provides Energy capacity to the item in which it is socketed. In Armor 2.0 for example, is implemented in a similar way to Masterworks, where visually it's a single area of the UI being clicked on to "Upgrade" to higher energy levels, but it's actually socketing new plugs.
Implementation
@JsonKey(name:'energyCapacity')
DestinyEnergyCapacityEntry? energyCapacity;