code: public PropertiesLoaderBuilder loadAllPropertiesFromSpring() {
          for (PropertySource<?> propertySource : env.getPropertySources()) {
              if (propertySource instanceof MapPropertySource) {
                  MapPropertySource mapPropSource = (MapPropertySource) propertySource;
                  for (String propName : mapPropSource.getPropertyNames()) {
                      if (!props.containsKey(propName)) {
                          props.put(propName, env.getProperty(propName));
                      }
                  }
              }
          }
          return this;
      }
docs: Loads all properties found for a given prefix.
  
  @return PropertyLoaderBuilder to continue the builder chain