Address more ConstantCaseForConstants warnings.

There are still so many more, but I ran out of steam.

Also, in Truth's `Platform` class, migrate off the deprecated `Splitter.onPattern`, and start using the now-non-`@Beta` `splitToList`.

PiperOrigin-RevId: 710073619

core/src/main/java/com/google/common/truth/Platform.java

@@ -121,8 +121,8 @@ static void cleanStackTrace(Throwable throwable) {
   private static final String DIFF_KEY = "diff (-expected +actual)";
 
   static @Nullable ImmutableList<Fact> makeDiff(String expected, String actual) {
-    ImmutableList<String> expectedLines = splitLines(expected);
-    ImmutableList<String> actualLines = splitLines(actual);
+    List<String> expectedLines = splitLines(expected);
+    List<String> actualLines = splitLines(actual);
     List<String> unifiedDiff =
         generateUnifiedDiff(expectedLines, actualLines, /* contextSize= */ 3);
     if (unifiedDiff.isEmpty()) {
@@ -137,11 +137,12 @@ static void cleanStackTrace(Throwable throwable) {
     return ImmutableList.of(fact(DIFF_KEY, result));
   }
 
-  private static ImmutableList<String> splitLines(String s) {
-    // splitToList is @Beta, so we avoid it.
-    return ImmutableList.copyOf(Splitter.onPattern("\r?\n").split(s));
+  private static List<String> splitLines(String s) {
+    return Splitter.on(NEWLINE_PATTERN).splitToList(s);
   }
 
+  private static final Pattern NEWLINE_PATTERN = Pattern.compile("\r?\n");
+
   abstract static class PlatformComparisonFailure extends ComparisonFailure {
     private final String message;
 

core/src/main/java/com/google/common/truth/Subject.java

@@ -449,12 +449,12 @@ private String formatActualOrExpected(@Nullable Object o) {
   private static String base16(byte[] bytes) {
     StringBuilder sb = new StringBuilder(2 * bytes.length);
     for (byte b : bytes) {
-      sb.append(hexDigits[(b >> 4) & 0xf]).append(hexDigits[b & 0xf]);
+      sb.append(hexDigitsUpper[(b >> 4) & 0xf]).append(hexDigitsUpper[b & 0xf]);
     }
     return sb.toString();
   }
 
-  private static final char[] hexDigits = "0123456789ABCDEF".toCharArray();
+  private static final char[] hexDigitsUpper = "0123456789ABCDEF".toCharArray();
 
   private static @Nullable Object arrayAsListRecursively(@Nullable Object input) {
     if (input instanceof Object[]) {
@@ -983,20 +983,20 @@ private boolean tryFailForEmptyString(@Nullable Object expected) {
 
   // From SourceCodeEscapers:
 
-  private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();
+  private static final char[] hexDigitsLower = "0123456789abcdef".toCharArray();
 
   private static char[] asUnicodeHexEscape(char c) {
     // Equivalent to String.format("\\u%04x", (int) c);
     char[] r = new char[6];
     r[0] = '\\';
     r[1] = 'u';
-    r[5] = HEX_DIGITS[c & 0xF];
+    r[5] = hexDigitsLower[c & 0xF];
     c = (char) (c >>> 4);
-    r[4] = HEX_DIGITS[c & 0xF];
+    r[4] = hexDigitsLower[c & 0xF];
     c = (char) (c >>> 4);
-    r[3] = HEX_DIGITS[c & 0xF];
+    r[3] = hexDigitsLower[c & 0xF];
     c = (char) (c >>> 4);
-    r[2] = HEX_DIGITS[c & 0xF];
+    r[2] = hexDigitsLower[c & 0xF];
     return r;
   }