The configprops endpoint provides information about configuration options that can be configured through application properties. It is basically a collated list of all @ConfigurationProperties. The following screenshot shows the configuration props in the HAL browser:

To illustrate a known example, the following section from the service response shows the configuration options that are available for Spring MVC:

"spring.mvc-org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties": {
          "prefix": "spring.mvc",
          "properties": {
            "contentnegotiation": {
              "favorPathExtension": false,
              "favorParameter": false,
              "mediaTypes": {
              }
            },
            "servlet": {
              "path": "/",
              "loadOnStartup": -1
            },
            "staticPathPattern": "/**",
            "dispatchOptionsRequest": true,
            "dispatchTraceRequest": false,
            "ignoreDefaultModelOnRedirect": true,
            "logResolvedException": false,
            "async": {
            },
            "view": {
            },
            "localeResolver": "ACCEPT_HEADER",
            "pathmatch": {
              "useSuffixPattern": false,
              "useRegisteredSuffixPattern": false
            },
            "throwExceptionIfNoHandlerFound": false
          }
   }