Update to check style 8.4 and ban org.mockito.ArgumentMatcher imports.

build.gradle

@@ -77,7 +77,7 @@ subprojects { project ->
     apply plugin: 'checkstyle'
 
     checkstyle {
-        toolVersion = '6.12.1'
+        toolVersion = '8.4'
     }
 
     checkstyle {

checkstyle.xml

@@ -94,8 +94,16 @@
         <!-- Prevent importing Mockito matchers directly -->
         <module name="IllegalImport">
             <property name="illegalPkgs" value="org.mockito.internal" />
-            <message key="import.illegal" value="Import from illegal package - {0}. Use org.mockito.Matchers to instantiate argument matchers; or org.hamcrest.Matchers for assertThat." />
+            <message key="import.illegal" value="Import from illegal package - {0}. Use org.mockito.Matchers to instantiate argument matchers." />
         </module>
+
+        <!-- ArgumentMatchers isn't available internally, the same methods are available on org.mockito.Mockito. -->
+        <module name="IllegalImport">
+            <property name="illegalClasses" value="org\.mockito\.ArgumentMatchers\..*" />
+            <property name="regexp" value="true" />
+            <message key="import.illegal" value="Import from illegal class - {0}. Use org.mockito.Mockito to statically import matcher methods." />
+        </module>
+
         <module name="ImportOrder">
           <!-- Checks for out of order import statements. -->
 
@@ -105,6 +113,7 @@
            <!-- This ensures that static imports go first. -->
            <property name="option" value="top"/>
            <property name="tokens" value="STATIC_IMPORT, IMPORT"/>
+           <property name="separated" value="true" />
          </module>
 
         <!-- Checks for whitespace. -->

library/src/main/java/com/bumptech/glide/RequestBuilder.java

@@ -230,7 +230,7 @@ public RequestBuilder<TranscodeType> thumbnail(
   @SuppressWarnings({"CheckResult", "unchecked"})
   @CheckResult
   public RequestBuilder<TranscodeType> thumbnail(
-      @Nullable RequestBuilder<TranscodeType> /*@Nullable*/ ... thumbnails) {
+      @Nullable RequestBuilder<TranscodeType>... thumbnails) {
     if (thumbnails == null || thumbnails.length == 0) {
       return thumbnail((RequestBuilder<TranscodeType>) null);
     }

samples/svg/src/main/java/com/bumptech/glide/samples/svg/SvgDecoder.java

@@ -6,7 +6,6 @@
 import com.bumptech.glide.load.resource.SimpleResource;
 import com.caverock.androidsvg.SVG;
 import com.caverock.androidsvg.SVGParseException;
-
 import java.io.IOException;
 import java.io.InputStream;