code: @Override
  	public List<ParsingError> doValidate() {
  
  		List<ParsingError> result = new ArrayList<> ();
  		if( Utils.isEmptyOrWhitespaces( this.newInstanceName ))
  			result.add( error( ErrorCode.CMD_MISSING_INSTANCE_NAME ));
  		else if( ! this.newInstanceName.matches( ParsingConstants.PATTERN_FLEX_ID ))
  			result.add( error( ErrorCode.CMD_INVALID_INSTANCE_NAME, name( this.newInstanceName )));
  
  		if( ! this.context.instanceExists( this.instancePath )) {
  			result.add( error( ErrorCode.CMD_NO_MATCHING_INSTANCE, instance( this.instancePath )));
  
  		} else {
  			String parentInstancePath = this.instancePath.replaceFirst( "/[^/]+$", "" );
  			String siblingPath = parentInstancePath + "/" + this.newInstanceName;
  			if( this.context.instanceExists( siblingPath ))
  				result.add( error( ErrorCode.CMD_CONFLICTING_INSTANCE_NAME, conflicting( siblingPath )));
  		}
  
  		return result;
  	}
docs: /*
  (non-Javadoc)
  @see net.roboconf.core.commands.AbstractCommandInstruction#doValidate()