Address some https://errorprone.info/bugpattern/UnnecessaryJavacSuppressWarnings warnings.

(And push a few class-level suppressions down to individual methods.)

I reverted some of the changes that Error Prone suggested. I'm a little unclear on various things:
- whether attempting to suppress `removal` warnings accomplishes anything under any compiler that we care about
- whether extending a deprecated type produces a warning under any compiler that we care about
- whether some deprecation warnings are showing up as "unnecessary" only because of builds against other sources of `java.*` classes that don't include the JDK's deprecations

Hopefully all the removals that I've kept in the CL are good.

RELNOTES=n/a
PiperOrigin-RevId: 712957106

Author: cpovirk

android/guava-tests/test/com/google/common/collect/ListsImplTest.java

@@ -243,7 +243,6 @@ private void checkLastIndexOf(List<?> toTest, int[] expected) {
   }
 
   @SafeVarargs
-  @SuppressWarnings("varargs")
   private final <T> List<T> createList(Class<T> listType, T... contents) {
     return getExample().createList(listType, asList(contents));
   }

android/guava-tests/test/com/google/common/collect/MapsTest.java

@@ -225,7 +225,6 @@ public void testLinkedHashMap() {
     assertEquals(emptyMap(), map);
   }
 
-  @SuppressWarnings("serial")
   public void testLinkedHashMapWithInitialMap() {
     Map<String, String> map =
         new LinkedHashMap<String, String>(
@@ -982,7 +981,6 @@ public void testUniqueIndexNullKey() {
 
   @J2ktIncompatible
   @GwtIncompatible // Maps.fromProperties
-  @SuppressWarnings("deprecation") // StringBufferInputStream
   public void testFromProperties() throws IOException {
     Properties testProp = new Properties();
 

android/guava/src/com/google/common/base/CharMatcher.java

@@ -1815,7 +1815,7 @@ public boolean matches(char c) {
       return predicate.apply(c);
     }
 
-    @SuppressWarnings("deprecation") // intentional; deprecation is for callers primarily
+    @Deprecated
     @Override
     public boolean apply(Character character) {
       return predicate.apply(checkNotNull(character));

android/guava/src/com/google/common/collect/MapMakerInternalMap.java

@@ -2873,7 +2873,6 @@ void writeMapTo(ObjectOutputStream out) throws IOException {
       out.writeObject(null); // terminate entries
     }
 
-    @SuppressWarnings("deprecation") // serialization of deprecated feature
     @J2ktIncompatible // java.io.ObjectInputStream
     MapMaker readMapMaker(ObjectInputStream in) throws IOException {
       int size = in.readInt();

android/guava/src/com/google/common/collect/NaturalOrdering.java

@@ -25,7 +25,6 @@
 
 /** An ordering that uses the natural order of the values. */
 @GwtCompatible(serializable = true)
-@SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
 final class NaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
   static final NaturalOrdering INSTANCE = new NaturalOrdering();
 
@@ -34,13 +33,15 @@ final class NaturalOrdering extends Ordering<Comparable<?>> implements Serializa
   @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsLast;
 
   @Override
+  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
   public int compare(Comparable<?> left, Comparable<?> right) {
     checkNotNull(left); // for GWT
     checkNotNull(right);
     return ((Comparable<Object>) left).compareTo(right);
   }
 
   @Override
+  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
   public <S extends Comparable<?>> Ordering<@Nullable S> nullsFirst() {
     Ordering<@Nullable Comparable<?>> result = nullsFirst;
     if (result == null) {
@@ -50,6 +51,7 @@ public int compare(Comparable<?> left, Comparable<?> right) {
   }
 
   @Override
+  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
   public <S extends Comparable<?>> Ordering<@Nullable S> nullsLast() {
     Ordering<@Nullable Comparable<?>> result = nullsLast;
     if (result == null) {
@@ -59,6 +61,7 @@ public int compare(Comparable<?> left, Comparable<?> right) {
   }
 
   @Override
+  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
   public <S extends Comparable<?>> Ordering<S> reverse() {
     return (Ordering<S>) ReverseNaturalOrdering.INSTANCE;
   }

android/guava/src/com/google/common/collect/ReverseNaturalOrdering.java

@@ -24,11 +24,11 @@
 
 /** An ordering that uses the reverse of the natural order of the values. */
 @GwtCompatible(serializable = true)
-@SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
 final class ReverseNaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
   static final ReverseNaturalOrdering INSTANCE = new ReverseNaturalOrdering();
 
   @Override
+  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
   public int compare(Comparable<?> left, Comparable<?> right) {
     checkNotNull(left); // right null is caught later
     if (left == right) {

android/guava/src/com/google/common/math/LongMath.java

@@ -1241,7 +1241,6 @@ private boolean testWitness(long base, long n) {
    *     is not precisely representable as a {@code double}
    * @since 30.0
    */
-  @SuppressWarnings("deprecation")
   @GwtIncompatible
   public static double roundToDouble(long x, RoundingMode mode) {
     // Logic adapted from ToDoubleRounder.

guava-tests/test/com/google/common/collect/ListsImplTest.java

@@ -243,7 +243,6 @@ private void checkLastIndexOf(List<?> toTest, int[] expected) {
   }
 
   @SafeVarargs
-  @SuppressWarnings("varargs")
   private final <T> List<T> createList(Class<T> listType, T... contents) {
     return getExample().createList(listType, asList(contents));
   }

guava-tests/test/com/google/common/collect/MapsTest.java

@@ -225,7 +225,6 @@ public void testLinkedHashMap() {
     assertEquals(emptyMap(), map);
   }
 
-  @SuppressWarnings("serial")
   public void testLinkedHashMapWithInitialMap() {
     Map<String, String> map =
         new LinkedHashMap<String, String>(
@@ -982,7 +981,6 @@ public void testUniqueIndexNullKey() {
 
   @J2ktIncompatible
   @GwtIncompatible // Maps.fromProperties
-  @SuppressWarnings("deprecation") // StringBufferInputStream
   public void testFromProperties() throws IOException {
     Properties testProp = new Properties();
 

guava/src/com/google/common/base/CharMatcher.java

@@ -1815,7 +1815,7 @@ public boolean matches(char c) {
       return predicate.apply(c);
     }
 
-    @SuppressWarnings("deprecation") // intentional; deprecation is for callers primarily
+    @Deprecated
     @Override
     public boolean apply(Character character) {
       return predicate.apply(checkNotNull(character));