Add a checkstyle lint banning wildcard imports (GTNewHorizons#220)

build.gradle

@@ -89,6 +89,23 @@ def out = services.get(StyledTextOutputFactory).create('an-output')
 def projectJavaVersion = JavaLanguageVersion.of(8)
 
 boolean disableSpotless = project.hasProperty("disableSpotless") ? project.disableSpotless.toBoolean() : false
+boolean disableCheckstyle = project.hasProperty("disableCheckstyle") ? project.disableCheckstyle.toBoolean() : false
+
+final String CHECKSTYLE_CONFIG = """
+<!DOCTYPE module PUBLIC
+  "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+  "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+<module name="Checker">
+  <module name="TreeWalker">
+    <!-- Use CHECKSTYLE:OFF and CHECKSTYLE:ON comments to suppress checkstyle lints in a block -->
+    <module name="SuppressionCommentFilter"/>
+    <module name="AvoidStarImport">
+      <!-- Allow static wildcard imports for cases like Opcodes and LWJGL classes, these don't get created accidentally by the IDE -->
+      <property name="allowStaticMemberImports" value="true"/>
+    </module>
+  </module>
+</module>
+"""
 
 checkPropertyExists("modName")
 checkPropertyExists("modId")
@@ -140,6 +157,17 @@ if (!disableSpotless) {
     apply from: Blowdryer.file('spotless.gradle')
 }
 
+if (!disableCheckstyle) {
+    apply plugin: 'checkstyle'
+    tasks.named("checkstylePatchedMc") { enabled = false }
+    tasks.named("checkstyleMcLauncher") { enabled = false }
+    tasks.named("checkstyleIdeVirtualMain") { enabled = false }
+    tasks.named("checkstyleInjectedTags") { enabled = false }
+    checkstyle {
+        config = resources.text.fromString(CHECKSTYLE_CONFIG)
+    }
+}
+
 String javaSourceDir = "src/main/java/"
 String scalaSourceDir = "src/main/scala/"
 String kotlinSourceDir = "src/main/kotlin/"

gradle.properties

@@ -140,6 +140,9 @@ curseForgeRelations =
 # That is, if there is no other active fork/upstream, NEVER change this.
 # disableSpotless = true
 
+# Uncomment this to disable checkstyle checks (currently wildcard import check).
+# disableCheckstyle = true
+
 # Override the IDEA build type. Valid value is "" (leave blank, do not override), "idea" (force use native IDEA build), "gradle"
 # (force use delegated build).
 # This is meant to be set in $HOME/.gradle/gradle.properties.