public Period getOccurrencePeriod() throws FHIRException { 
      if (this.occurrence == null)
        this.occurrence = new Period();
      if (!(this.occurrence instanceof Period))
        throw new FHIRException("Type mismatch: the type Period was expected, but "+this.occurrence.getClass().getName()+" was encountered");
      return (Period) this.occurrence;
    }
public Period getOccurrencePeriod ( ) throws FHIRException { if ( this . occurrence == null ) this . occurrence = new Period ( ) ; if ( ! ( this . occurrence instanceof Period ) ) throw new FHIRException ( "Type mismatch: the type Period was expected, but " + this . occurrence . getClass ( ) . getName ( ) + " was encountered" ) ; return ( Period ) this . occurrence ; }
@return {@link #occurrence} (The time when this communication is to occur.)