static _extractProjections(imageryLayers) {
    //>>includeStart('debug', pragmas.debug);
    Check.defined("imageryLayers", imageryLayers);
    //>>includeEnd('debug');

    const projections = [];
    const length = imageryLayers.length;
    for (let i = 0; i < length; i++) {
      const imageryLayer = imageryLayers.get(i);
      const projection = ModelPrimitiveImagery._getProjection(imageryLayer);
      projections.push(projection);
    }
    return projections;
  }
Computes an array containing the projections that are used in
the given imagery layers.

(Note that this array may contain duplicates)

@param {ImageryLayerCollection} imageryLayers The imagery layers
@returns {MapProjection[]} The projections
@private