Fix reference to assets on the default branch in ref doc

See gh-26863

src/docs/asciidoc/index.adoc

@@ -1,6 +1,9 @@
 = Spring Framework Documentation
 :doc-root: https://docs.spring.io
+:github-repo: spring-projects/spring-framework
+
 :api-spring-framework: {doc-root}/spring-framework/docs/{spring-version}/javadoc-api/org/springframework
+:spring-framework-main-code: https://github.com/{github-repo}/tree/main
 
 ****
 _What's New_, _Upgrade Notes_, _Supported Versions_, and other topics,

src/docs/asciidoc/overview.adoc

@@ -135,8 +135,7 @@ https://github.com/spring-projects/spring-framework[Github]. However, please kee
 that, for all but the most trivial issues, we expect a ticket to be filed in the issue
 tracker, where discussions take place and leave a record for future reference.
 
-For more details see the guidelines at the
-https://github.com/spring-projects/spring-framework/blob/master/CONTRIBUTING.md[CONTRIBUTING],
+For more details see the guidelines at the {spring-framework-main-code}/CONTRIBUTING.md[CONTRIBUTING],
 top-level project page.
 
 

src/docs/asciidoc/testing.adoc

@@ -7573,9 +7573,9 @@ of testing even within the same project.
 ===== Further Examples
 
 The framework's own tests include
-https://github.com/spring-projects/spring-framework/tree/master/spring-test/src/test/java/org/springframework/test/web/servlet/samples[
+{spring-framework-main-code}/spring-test/src/test/java/org/springframework/test/web/servlet/samples[
 many sample tests] intended to show how to use MockMvc on its own or through the
-https://github.com/spring-projects/spring-framework/tree/master/spring-test/src/test/java/org/springframework/test/web/servlet/samples/client[
+{spring-framework-main-code}/spring-test/src/test/java/org/springframework/test/web/servlet/samples/client[
 WebTestClient]. Browse these examples for further ideas.
 
 
@@ -8784,7 +8784,7 @@ configuration. Check for the support for code completion on static members.
 ==== Further Examples of Client-side REST Tests
 
 Spring MVC Test's own tests include
-https://github.com/spring-projects/spring-framework/tree/master/spring-test/src/test/java/org/springframework/test/web/client/samples[example
+{spring-framework-main-code}/spring-test/src/test/java/org/springframework/test/web/client/samples[example
 tests] of client-side REST tests.
 
 

src/docs/asciidoc/web/webflux-view.adoc

@@ -380,8 +380,8 @@ The following example shows how compile a template:
 ----
 
 Check out the Spring Framework unit tests,
-https://github.com/spring-projects/spring-framework/tree/master/spring-webflux/src/test/java/org/springframework/web/reactive/result/view/script[Java], and
-https://github.com/spring-projects/spring-framework/tree/master/spring-webflux/src/test/resources/org/springframework/web/reactive/result/view/script[resources],
+{spring-framework-main-code}/spring-webflux/src/test/java/org/springframework/web/reactive/result/view/script[Java], and
+{spring-framework-main-code}/spring-webflux/src/test/resources/org/springframework/web/reactive/result/view/script[resources],
 for more configuration examples.
 
 

src/docs/asciidoc/web/webflux-webclient.adoc

@@ -1130,7 +1130,7 @@ controller method .
 To test code that uses the `WebClient`, you can use a mock web server, such as the
 https://github.com/square/okhttp#mockwebserver[OkHttp MockWebServer]. To see an example
 of its use, check out
-https://github.com/spring-projects/spring-framework/blob/master/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java[`WebClientIntegrationTests`]
+{spring-framework-main-code}/spring-webflux/src/test/java/org/springframework/web/reactive/function/client/WebClientIntegrationTests.java[`WebClientIntegrationTests`]
 in the Spring Framework test suite or the
 https://github.com/square/okhttp/tree/master/samples/static-server[`static-server`]
 sample in the OkHttp repository.

src/docs/asciidoc/web/webflux.adoc

@@ -9,11 +9,10 @@ https://www.reactive-streams.org/[Reactive Streams] back pressure, and runs on s
 Netty, Undertow, and Servlet 3.1+ containers.
 
 Both web frameworks mirror the names of their source modules
-(https://github.com/spring-projects/spring-framework/tree/master/spring-webmvc[spring-webmvc] and
-https://github.com/spring-projects/spring-framework/tree/master/spring-webflux[spring-webflux])
-and co-exist side by side in the Spring Framework. Each module is optional.
-Applications can use one or the other module or, in some cases, both --
-for example, Spring MVC controllers with the reactive `WebClient`.
+({spring-framework-main-code}/spring-webmvc[spring-webmvc] and
+{spring-framework-main-code}/spring-webflux[spring-webflux]) and co-exist side by side in the
+Spring Framework. Each module is optional. Applications can use one or the other module or,
+in some cases, both -- for example, Spring MVC controllers with the reactive `WebClient`.
 
 
 

src/docs/asciidoc/web/webmvc-view.adoc

@@ -822,8 +822,8 @@ template engine configuration, for example). The following example shows how to
 ----
 
 Check out the Spring Framework unit tests,
-https://github.com/spring-projects/spring-framework/tree/master/spring-webmvc/src/test/java/org/springframework/web/servlet/view/script[Java], and
-https://github.com/spring-projects/spring-framework/tree/master/spring-webmvc/src/test/resources/org/springframework/web/servlet/view/script[resources],
+{spring-framework-main-code}/spring-webmvc/src/test/java/org/springframework/web/servlet/view/script[Java], and
+{spring-framework-main-code}/spring-webmvc/src/test/resources/org/springframework/web/servlet/view/script[resources],
 for more configuration examples.
 
 

src/docs/asciidoc/web/webmvc.adoc

@@ -5,12 +5,12 @@
 Spring Web MVC is the original web framework built on the Servlet API and has been included
 in the Spring Framework from the very beginning. The formal name, "`Spring Web MVC,`"
 comes from the name of its source module
-(https://github.com/spring-projects/spring-framework/tree/master/spring-webmvc[`spring-webmvc`]),
+({spring-framework-main-code}/spring-webmvc[`spring-webmvc`]),
 but it is more commonly known as "`Spring MVC`".
 
 Parallel to Spring Web MVC, Spring Framework 5.0 introduced a reactive-stack web framework
 whose name, "`Spring WebFlux,`" is also based on its source module
-(https://github.com/spring-projects/spring-framework/tree/master/spring-webflux[`spring-webflux`]).
+({spring-framework-main-code}/spring-webflux[`spring-webflux`]).
 This section covers Spring Web MVC. The <<web-reactive.adoc#spring-web-reactive, next section>>
 covers Spring WebFlux.
 
@@ -301,7 +301,7 @@ Applications can declare the infrastructure beans listed in <<mvc-servlet-specia
 that are required to process requests. The `DispatcherServlet` checks the
 `WebApplicationContext` for each special bean. If there are no matching bean types,
 it falls back on the default types listed in
-https://github.com/spring-projects/spring-framework/blob/master/spring-webmvc/src/main/resources/org/springframework/web/servlet/DispatcherServlet.properties[`DispatcherServlet.properties`].
+{spring-framework-main-code}/spring-webmvc/src/main/resources/org/springframework/web/servlet/DispatcherServlet.properties[`DispatcherServlet.properties`].
 
 In most cases, the <<mvc-config>> is the best starting point. It declares the required
 beans in either Java or XML and provides a higher-level configuration callback API to