Grab most of the low-hanging fruit.

gradle/checkstyle.gradle

@@ -1,4 +1,8 @@
 checkstyle {
     toolVersion '8.14'
     configFile new File(project.rootDir, ['config', 'checkstyle', 'checkstyle.xml'].join(File.separator))
+    
+    // The build should immediately fail if we have errors.
+    maxErrors = 0
+    maxWarnings = 0
 }