code: public static DynamicProperty getInstance(String propName) {
          // This is to ensure that a configuration source is registered with
          // DynamicProperty
          if (dynamicPropertySupportImpl == null) {
              DynamicPropertyFactory.getInstance();
          }
          DynamicProperty prop = ALL_PROPS.get(propName);
          if (prop == null) {
              prop = new DynamicProperty(propName);
              DynamicProperty oldProp = ALL_PROPS.putIfAbsent(propName, prop);
              if (oldProp != null) {
                  prop = oldProp;
              }
          }
          return prop;
      }
docs: Gets the DynamicProperty for a given property name.
  This may be a previously constructed object,
  or an object constructed on-demand to satisfy the request.
  
  @param propName the name of the property
  @return a DynamicProperty object that holds the cached value of
  the configuration property named {@code propName}