code: @Override
  	public void updateContext() {
  
  		String newValue = replaceVariables( this.value, this.context, this.instancePath );
  		if( newValue != null ) {
  			this.context.variables.put( this.key, newValue );
  		}
  
  		// When not resolved, we disable it.
  		// We also replace it by a mock value so that we can perform
  		// validation. It implies populating the context.
  		else {
  			setDisabled( true );
  			this.context.disabledVariables.add( this.key );
  			this.context.variables.put( this.key, "fake" );
  			String path = "/fake";
  			if( this.instancePath != null )
  				path = this.instancePath + path;
  
  			this.context.instancePathToComponentName.put( path, FAKE_COMPONENT_NAME );
  		}
  	}
docs: /*
  (non-Javadoc)
  @see net.roboconf.core.commands.AbstractCommandInstruction#updateContext()