Take review comments.

src/main/kotlin/lgbt/mystic/foundation/concrete/ConcretePluginPlugin.kt

@@ -11,7 +11,7 @@ class ConcretePluginPlugin : ConcreteProjectPlugin() {
 
     project.plugins.apply("com.github.johnrengelman.shadow")
 
-    (project.tasks.getByName("processResources") as ProcessResources).apply {
+    project.tasks.find<ProcessResources>("processResources")!!.apply {
       val props = mapOf("version" to project.version.toString())
       inputs.properties(props)
       filteringCharset = "UTF-8"
@@ -24,7 +24,7 @@ class ConcretePluginPlugin : ConcreteProjectPlugin() {
       archiveClassifier.set("plugin")
     }
 
-    project.tasks["assemble"].dependsOn(project.tasks["shadowJar"])
+    project.tasks.addTaskDependency("assemble", "shadowJar")
 
     project.concreteRootProject.tasks["setupPaperServer"].dependsOn(project.tasks["shadowJar"])
   }

src/main/kotlin/lgbt/mystic/foundation/concrete/RunPaperServer.kt

@@ -1,6 +1,7 @@
 package lgbt.mystic.foundation.concrete
 
 import org.gradle.api.DefaultTask
+import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.TaskAction
 import org.gradle.kotlin.dsl.getByType
 import java.io.File
@@ -11,6 +12,12 @@ open class RunPaperServer : DefaultTask() {
     outputs.upToDateWhen { false }
   }
 
+  @get:Input
+  var additionalServerArguments = mutableListOf<String>()
+
+  @get:Input
+  var disableServerGui = true
+
   @TaskAction
   fun runPaperServer() {
     val concrete = project.extensions.getByType<ConcreteExtension>()
@@ -22,7 +29,14 @@ open class RunPaperServer : DefaultTask() {
     project.javaexec {
       classpath(paperJarFile.absolutePath)
       workingDir(minecraftServerDirectory)
-      args("nogui")
+
+      val allServerArguments = mutableListOf<String>()
+      allServerArguments.addAll(additionalServerArguments)
+      if (disableServerGui) {
+        allServerArguments.add("nogui")
+      }
+
+      args(allServerArguments)
       mainClass.set(mainClassName)
     }
   }

src/main/kotlin/lgbt/mystic/foundation/concrete/extensions.kt

@@ -7,9 +7,20 @@ import org.gradle.api.tasks.TaskOutputs
 import java.nio.file.FileSystems
 import java.nio.file.Path
 
+/**
+ * Checks if the project has the [ConcretePluginPlugin] applied.
+ */
 internal fun Project.isPluginProject() = plugins.hasPlugin(ConcretePluginPlugin::class.java)
+
+/**
+ * Finds all projects in the project's hierarchy that are plugins.
+ */
 internal fun Project.findPluginProjects() = allprojects.filter { project -> project.isPluginProject() }
 
+internal fun TaskContainer.addTaskDependency(dependent: String, dependency: String) {
+  getByName(dependent).dependsOn(getByName(dependency))
+}
+
 internal inline fun <reified T> TaskContainer.find(name: String) =
   findByName(name) as T?
 
@@ -26,6 +37,10 @@ internal val Project.concreteRootExtension: ConcreteExtension
     error = { "Failed to find concrete root. Did you apply the concrete root plugin?" }
   )
 
+/**
+ * Finds the concrete root project, which is the first project in the project hierarchy
+ * that has the concrete extension.
+ */
 internal val Project.concreteRootProject: Project
   get() = findTargetParent(
     valid = { extensions.findByType(ConcreteExtension::class.java) != null },
@@ -33,6 +48,11 @@ internal val Project.concreteRootProject: Project
     error = { "Failed to find concrete root. Did you apply the concrete root plugin?" }
   )
 
+/**
+ * Scans a project hierarchy looking for a project matching the criteria specified in [valid].
+ * If found, [extract] is called and the result is returned. If no matching project is found, [error] is called
+ * and passed to RuntimeException as an error string.
+ */
 internal fun <T> Project.findTargetParent(valid: Project.() -> Boolean, extract: Project.() -> T, error: () -> String): T {
   if (valid(this)) {
     return extract(this)