Fix up some module dependencies

Author: tvernum

x-pack/plugin/core/build.gradle

@@ -53,7 +53,14 @@ dependencies {
   api "org.apache.httpcomponents.client5:httpclient5:${versions.httpclient5}"
   api "org.apache.httpcomponents.core5:httpcore5:${versions.httpcore5}"
   api "org.apache.httpcomponents.core5:httpcore5-h2:${versions.httpcore5}"
-  runtimeOnly "org.slf4j:slf4j-api:${versions.slf4j}"
+
+  // Ideally this would be `runtimeOnly` so that we don't accidentally write code against the SLF4j API
+  // However, some child plugins (like security) need to use slf4j directly in order to manage logging for their dependencies :(
+  // And due to the way our plugin loading handles java modules between dependent plugins, this plugin (x-pack-core) needs to declare
+  //  a module dependency on slf4j (`requires org.slf4j`) so that security can also be dependent on it
+  // And having a module dependency counts as using the jar, so we can't make it `runtimeOnly` :(
+
+  implementation "org.slf4j:slf4j-api:${versions.slf4j}"
   runtimeOnly "org.apache.logging.log4j:log4j-slf4j-impl:${versions.log4j}"
 
   api "commons-logging:commons-logging:${versions.commonslogging}"
@@ -71,9 +78,6 @@ dependencies {
   implementation project(":x-pack:plugin:core:template-resources")
 
   testImplementation "org.elasticsearch:mocksocket:${versions.mocksocket}"
-  testImplementation "org.apache.logging.log4j:log4j-slf4j-impl:${versions.log4j}"
-  // this might suffer from https://github.com/elastic/elasticsearch/issues/93714
-  testImplementation "org.slf4j:slf4j-api:${versions.slf4j}"
   testImplementation project(path: ':modules:reindex')
   testImplementation project(path: ':modules:parent-join')
   testImplementation project(path: ':modules:lang-mustache')

x-pack/plugin/core/src/main/java/module-info.java

@@ -25,6 +25,7 @@
     requires org.elasticsearch.xcore.templates;
     requires org.apache.httpcomponents.client5.httpclient5;
     requires org.apache.httpcomponents.core5.httpcore5;
+    requires org.slf4j;
 
     exports org.elasticsearch.index.engine.frozen;
     exports org.elasticsearch.license;

x-pack/plugin/identity-provider/build.gradle

@@ -45,9 +45,8 @@ dependencies {
       exclude group: 'org.bouncycastle'
   }
 
-  api "org.slf4j:slf4j-api:${versions.slf4j}"
-  runtimeOnly "org.slf4j:slf4j-nop:${versions.slf4j}"
-  //  runtimeOnly("org.apache.logging.log4j:log4j-slf4j-impl:${versions.log4j}") https://github.com/elastic/elasticsearch/issues/93714
+  implementation "org.slf4j:slf4j-api:${versions.slf4j}"
+  runtimeOnly("org.apache.logging.log4j:log4j-slf4j-impl:${versions.log4j}")
   api "org.apache.httpcomponents:httpclient:${versions.httpclient}"
   api "org.apache.httpcomponents:httpcore:${versions.httpcore}"
   api "org.apache.httpcomponents:httpasyncclient:${versions.httpasyncclient}"

x-pack/plugin/security/build.gradle

@@ -64,9 +64,9 @@ dependencies {
   api ( "org.cryptacular:cryptacular:1.2.5") {
     exclude group: 'org.bouncycastle'
   }
-  api "org.slf4j:slf4j-api:${versions.slf4j}"
-  runtimeOnly "org.slf4j:slf4j-nop:${versions.slf4j}" // workaround for https://github.com/elastic/elasticsearch/issues/93714
-  // api "org.apache.logging.log4j:log4j-slf4j-impl:${versions.log4j}"  see above
+
+  implementation "org.slf4j:slf4j-api:${versions.slf4j}"
+  runtimeOnly "org.apache.logging.log4j:log4j-slf4j-impl:${versions.log4j}"
 
   api "org.apache.httpcomponents:httpclient:${versions.httpclient}"
   api "org.apache.httpcomponents:httpcore:${versions.httpcore}"