Conditional declaration in AirvolumeMixed

[MatthewSZhang]

I found a conditional declaration of in BuildingSystems.Buildings.Airvolumes.AirvoumeMixed shown as:
"BuildingSystems.Buildings.Airvolumes.MixingVolumeMoistAir air(
redeclare package Medium = Medium,
geometryType=geometryType,
V=V,
m_flow_nominal=0.1,
nPorts=nAirpaths,
T_start=T_start[1],
X_start={x_start[1],1-x_start[1]},
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial,
massDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial) if
TSou == BuildingSystems.Buildings.Types.DataSource.Calculation
"Mixed air volume of moist air"
annotation (Placement(transformation(extent={{-10,-10},{10,10}})));"

Then the component 'air' is used in
" Modelica.Blocks.Sources.RealExpression pAir(
y=air.p)
annotation (Placement(transformation(extent={{44,50},{64,70}})));"

The issue is that Modelica Language Specification (Version 3.4), Section 4.4.5, said, "A component declared with a condition-attribute can only be modified and/or used in connections", but why when I tested it in BuildingSystems.Applications.HeatingSystems.WaterHeatingSystem, no error appears in Dymola.

Is it a bug in AirvolumeMixed, but Dymola for some reason bypasses it, or it is a correct usage of conditional declaration?