Update Kotlin to 1.7.10

Closes gh-11374, gh-11534

config/spring-security-config.gradle

@@ -110,8 +110,8 @@ rncToXsd {
 
 tasks.withType(KotlinCompile).configureEach {
 	kotlinOptions {
-		languageVersion = "1.6"
-		apiVersion = "1.6"
+		languageVersion = "1.7"
+		apiVersion = "1.7"
 		freeCompilerArgs = ["-Xjsr305=strict", "-Xsuppress-version-warnings"]
 		jvmTarget = "17"
 	}

config/src/main/kotlin/org/springframework/security/config/annotation/web/session/SessionFixationDsl.kt

@@ -73,6 +73,7 @@ class SessionFixationDsl {
                     SessionFixationStrategy.MIGRATE -> sessionFixation.migrateSession()
                     SessionFixationStrategy.CHANGE_ID -> sessionFixation.changeSessionId()
                     SessionFixationStrategy.NONE -> sessionFixation.none()
+                    null -> null
                 }
             }
         }