Add dependency between rncToXsd and sourcesJar

Since processResources is configured directly instead of via the source
set container, an explicit dependency task between rncToXsd and
sourcesJar must be defined.

Issue gh-13845

config/spring-security-config.gradle

@@ -133,6 +133,13 @@ tasks.named('processResources', ProcessResources).configure {
 	}
 }
 
+tasks.named('sourcesJar', Jar).configure {
+	from(rncToXsd) {
+		duplicatesStrategy DuplicatesStrategy.EXCLUDE
+		into 'org/springframework/security/config/'
+	}
+}
+
 tasks.withType(KotlinCompile).configureEach {
 	kotlinOptions {
 		languageVersion = "1.3"