Upgraded Gradle Shadow plugin to 4.0.4 (last Gradle 4.x version)

build.gradle

@@ -3,7 +3,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.github.jengelman.gradle.plugins:shadow:2.0.4'
+        classpath 'com.github.jengelman.gradle.plugins:shadow:4.0.4'
     }
 }
 

proxy/build.gradle

@@ -1,6 +1,5 @@
 plugins {
     id 'java'
-    id 'de.sebastianboegl.shadow.transformer.log4j' version '2.1.1'
     id 'checkstyle'
 }
 
@@ -20,6 +19,10 @@ jar {
     }
 }
 
+shadowJar {
+    transform(com.github.jengelman.gradle.plugins.shadow.transformers.Log4j2PluginsCacheFileTransformer)
+}
+
 tasks.withType(Checkstyle) {
     exclude('**/com/velocitypowered/proxy/protocol/packet/*.java')
 }