code: @Override
  	public void setProperty(final String name, final Object value) {
  
  		final Properties properties = getProperties();
  		boolean hasChanges          = false;
  
  		if (value == null) {
  
  			if (properties.containsKey(name)) {
  
  				properties.remove(name);
  				hasChanges = true;
  			}
  
  		} else {
  
  			properties.setProperty(name, value.toString());
  			hasChanges = true;
  		}
  
  		if (hasChanges) {
  
  			final File propertiesFile   = new File(databasePath + "/graph.properties");
  
  			try (final Writer writer = new FileWriter(propertiesFile)) {
  
  				properties.store(writer, "Created by Structr at " + new Date());
  
  			} catch (IOException ioex) {
  
  				logger.warn("Unable to write properties file", ioex);
  			}
  		}
  	}
docs: ----- interface GraphProperties -----