Add static imports to code snippets

Closes gh-6597

docs/modules/ROOT/pages/reactive/test/web/authentication.adoc

@@ -7,6 +7,8 @@ For example:
 .Java
 [source,java,role="primary"]
 ----
+import static org.springframework.security.test.web.reactive.server.SecurityMockServerConfigurers.mockUser;
+
 @Test
 public void messageWhenNotAuthenticated() throws Exception {
 	this.rest
@@ -67,6 +69,7 @@ public void messageWhenMutateWithMockAdminThenOk() throws Exception {
 [source,kotlin,role="secondary"]
 ----
 import org.springframework.test.web.reactive.server.expectBody
+import org.springframework.security.test.web.reactive.server.SecurityMockServerConfigurers.mockUser
 
 //...
 

docs/modules/ROOT/pages/reactive/test/web/csrf.adoc

@@ -7,6 +7,8 @@ For example:
 .Java
 [source,java,role="primary"]
 ----
+import static org.springframework.security.test.web.reactive.server.SecurityMockServerConfigurers.csrf;
+
 this.rest
 	// provide a valid CSRF token
 	.mutateWith(csrf())
@@ -18,6 +20,8 @@ this.rest
 .Kotlin
 [source,kotlin,role="secondary"]
 ----
+import org.springframework.security.test.web.reactive.server.SecurityMockServerConfigurers.csrf
+
 this.rest
     // provide a valid CSRF token
     .mutateWith(csrf())

docs/modules/ROOT/pages/reactive/test/web/setup.adoc

@@ -6,6 +6,9 @@ The basic setup looks like this:
 .Java
 [source,java,role="primary"]
 ----
+import static org.springframework.security.test.web.reactive.server.SecurityMockServerConfigurers.springSecurity;
+import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;
+
 @ExtendWith(SpringExtension.class)
 @ContextConfiguration(classes = HelloWebfluxMethodApplication.class)
 public class HelloWebfluxMethodApplicationTests {
@@ -31,6 +34,9 @@ public class HelloWebfluxMethodApplicationTests {
 .Kotlin
 [source,kotlin,role="secondary"]
 ----
+import org.springframework.security.test.web.reactive.server.SecurityMockServerConfigurers.springSecurity
+import org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication
+
 @ExtendWith(SpringExtension::class)
 @ContextConfiguration(classes = [HelloWebfluxMethodApplication::class])
 class HelloWebfluxMethodApplicationTests {