fix hash function and write it in a clearer, more explicit style

Author: ben-manes

caffeine/src/main/java/com/github/benmanes/caffeine/cache/FrequencySketch.java

@@ -167,14 +167,19 @@ public void increment(E e) {
 
   /** Applies a supplemental hash functions to defends against poor quality hash. */
   int spread(int x) {
-    x = ((x >>> 17) ^ x) * 0xed5ad4bb;
-    x = ((x >>> 11) ^ x) * 0xac4c1b51;
-    return (x >>> 15) ^ x;
+    x ^= x >>> 17;
+    x *= 0xed5ad4bb;
+    x ^= x >>> 11;
+    x *= 0xac4c1b51;
+    x ^= x >>> 15;
+    return x;
   }
 
   /** Applies another round of hashing for additional randomization. */
   int rehash(int x) {
-    return 0x31848bab * (x >>> 14) ^ x;
+    x *= 0x31848bab;
+    x ^= x >>> 14;
+    return x;
   }
 
   /**

gradle/dependencies.gradle

@@ -87,7 +87,7 @@ ext {
   ]
   pluginVersions = [
     bnd: '6.3.1',
-    checkstyle: '10.3.3',
+    checkstyle: '10.3.4',
     coveralls: '2.12.0',
     dependencyCheck: '7.2.1',
     errorprone: '2.0.2',