code: private String getPropertyValue(String name) {
  
          // Check for corresponding environment variable if overrides enabled
          if (environmentPropertiesEnabled) {
  
              // Transform the name according to common convention
              final String envName = name.replace('-', '_').toUpperCase();
              final String envValue = System.getenv(envName);
  
              if (envValue != null) {
                  return envValue;
              }
          }
  
          return properties.getProperty(name);
      }
docs: Gets the string value for a property name.
  
  The value may come from either the OS environment (if property override
  is enabled) or the Properties collection that was loaded from
  guacamole.properties. When checking the environment for the named
  property, the name is first transformed by converting all hyphens to
  underscores and converting the string to upper case letter, in accordance
  with common convention for environment strings.
  
  @param name
  The name of the property value to retrieve.
  
  @return
  The corresponding value for the property. If property override
  is enabled and the value is found in the OS environment, the value
  from the environment is returned. Otherwise, the value from
  guacamole.properties, if any, is returned.