***************************************************************************
@method _validate
@description Validates that required properties are present
@throws Error
function() {
    if (!_.isString(this.name)) {
      throw new TypeError(`OperationParameter.name (${this.name}) is required`)
    }
    if (!_.isString(this.location) || !_.includes(VALID_LOCATIONS, this.location)) {
      throw new TypeError(`OperationParameter.location (${this.location}) ` +
                          `is required and should be one of: ${VALID_LOCATIONS}`)
    }
  }