Swagger UI resources are incorrectly mapped when using WebJar prefix or Swagger root path

[jamesmissen]

Describe the bug

Issue #2969 and pull #2970 attempt to apply the same SpringDoc transformations to the SpringDoc resources under /webjars/**.

In addition, commit e3b4311 modifies the mappings for SpringDoc resources in WebFlux if the springdoc.webjars.prefix property is altered.

However, these changes have multiple issues:

• The uiRootPath is erroneously added to the front of the pattern. E.g. if the Swagger path is /documentation/spring-doc.html, then the WebJar resources will be at /documentation/webjars/** instead of /webjars/**.

  springdoc-openapi/springdoc-openapi-starter-webflux-ui/src/main/java/org/springdoc/webflux/ui/SwaggerWebFluxConfigurer.java

  Line 119 in 4b95d0e

  registry.addResourceHandler(uiRootPath + swaggerUiWebjarsPrefix + ALL_PATTERN)

• The swaggerUiPrefix value is set to the same as swaggerUiWebjarsPrefix when springdoc.webjars.prefix is not /webjars. The swaggerUiPrefix pattern should not be affected by the WebJars prefix value.

  springdoc-openapi/springdoc-openapi-starter-webflux-ui/src/main/java/org/springdoc/webflux/ui/SwaggerWebFluxConfigurer.java

  Lines 114 to 116 in 4b95d0e

  	swaggerUiPrefix = webjarsPrefix;
  	resourcePath = DEFAULT_WEB_JARS_PREFIX_URL + DEFAULT_PATH_SEPARATOR;
  	swaggerUiWebjarsPrefix = swaggerUiPrefix;

• The springdoc.webjars.prefix property is unnecessary and confusing. It is only currently used for WebFlux and not WebMvc, when the behaviour of WebJars is the same for both.

  It also doesn't make sense to have, as the mappings for WebJar resources on the classpath are already configured using Spring config properties:

  • spring.web.resources.add-mappings control whether the WebJar resources are actually exposed.
  • spring.mvc.webjars-path-pattern and spring.webflux.webjars-path-pattern set the pattern to expose WebJar resources (the default is /webjars/**) - hence another property for the same value is not needed.

  WebFlux reference: https://github.com/spring-projects/spring-boot/blob/3d8c4390915edcd0c279de3b742f5260983a6fa7/module/spring-boot-webflux/src/main/java/org/springframework/boot/webflux/autoconfigure/WebFluxAutoConfiguration.java#L234-L247

  WebMvc reference: https://github.com/spring-projects/spring-boot/blob/3d8c4390915edcd0c279de3b742f5260983a6fa7/module/spring-boot-webmvc/src/main/java/org/springframework/boot/webmvc/autoconfigure/WebMvcAutoConfiguration.java#L352-L357

• The uiRootPath for the resource handler patterns is computed incorrectly. For the resource mappings the actuator base path is added last, instead of first. For the consumers (i.e. the subclasses of AbstractSwaggerWelcome), the actuator base path is added first.

  E.g. if the Swagger path is /documentation/spring-doc.html, and the actuator base path is /actuator, then SwaggerWelcomeCommon will redirect to /actuator/documentation/swagger-ui/index.html as expected, but the index resource will be actually be exposed at /documentation/actuator/swagger-ui/index.html.

  springdoc-openapi/springdoc-openapi-starter-webflux-ui/src/main/java/org/springdoc/webflux/ui/SwaggerWebFluxConfigurer.java

  Lines 98 to 103 in 4b95d0e

  	StringBuilder uiRootPath = new StringBuilder();
  	String swaggerPath = swaggerUiConfigProperties.getPath();
  	if (swaggerPath.contains(DEFAULT_PATH_SEPARATOR))
  	uiRootPath.append(swaggerPath, 0, swaggerPath.lastIndexOf(DEFAULT_PATH_SEPARATOR));
  	if (actuatorProvider.isPresent() && actuatorProvider.get().isUseManagementPort())
  	uiRootPath.append(actuatorProvider.get().getBasePath());

  springdoc-openapi/springdoc-openapi-starter-common/src/main/java/org/springdoc/ui/AbstractSwaggerWelcome.java

  Lines 193 to 198 in 4b95d0e

  	if (ArrayUtils.isNotEmpty(sbUrls))
  	sbUrl = sbUrls[0];
  	String swaggerPath = swaggerUiConfigParameters.getPath();
  	if (swaggerPath.contains(DEFAULT_PATH_SEPARATOR))
  	sbUrl.append(swaggerPath, 0, swaggerPath.lastIndexOf(DEFAULT_PATH_SEPARATOR));
  	swaggerUiConfigParameters.setUiRootPath(sbUrl.toString());

To Reproduce
Steps to reproduce the behavior:

• Clone the latest version (i.e. 3.0.0-RC1).

• Add the property "springdoc.swagger-ui.path=/documentation/swagger-ui.html" to the springdoc-openapi-starter-webflux-ui test app34 (from pull ISSUE-2969 fix path to register resource handler to work SwaggerIndexPageTransformer considering /webjar path prefix #2970), and it will fail.

  springdoc-openapi/springdoc-openapi-starter-webflux-ui/src/test/java/test/org/springdoc/ui/app34/SpringDocApp34Test.java

  Line 36 in 4b95d0e

  @TestPropertySource(properties = "springdoc.swagger-ui.disable-swagger-default-url=true")

Expected behavior

• The springdoc.webjars.prefix should not affect the normal (non-WebJar) mappings to the Swagger UI resources.

• The behaviour of the WebJars prefix should be the same for WebFlux and WebMvc, as both map WebJar resources to /webjars/** by default (i.e. it's not specific to WebFlux only).

• The properties spring.mvc.webjars-path-pattern and spring.webflux.webjars-path-pattern should be used instead of springdoc.webjars.prefix.

• The /webjars/swagger-ui/** mapping should not be added if resource mappings at /webjars/** have been disabled (i.e. if spring.web.resources.add-mappings is set to false).

[jamesmissen]

I have created PR #3146 to fix the aforementioned issues.