Make NoCanIgnoreReturnValueOnClasses non-suppressible.

#checkreturnvalue

PiperOrigin-RevId: 506882237

annotations/src/main/java/com/google/errorprone/annotations/CanIgnoreReturnValue.java

@@ -26,12 +26,13 @@
 import java.lang.annotation.Target;
 
 /**
- * Indicates that the return value of the annotated API(s) can be safely ignored.
+ * Indicates that the return value of the annotated API is ignorable.
  *
  * <p>This is the opposite of {@link CheckReturnValue}. It can be used inside classes or packages
  * annotated with {@code @CheckReturnValue} to exempt specific APIs from the default.
  */
 @Documented
+// Note: annotating a type with @CanIgnoreReturnValue is discouraged (and banned inside of Google)
 @Target({METHOD, CONSTRUCTOR, TYPE})
 @Retention(CLASS)
 public @interface CanIgnoreReturnValue {}

core/src/main/java/com/google/errorprone/bugpatterns/checkreturnvalue/NoCanIgnoreReturnValueOnClasses.java

@@ -68,6 +68,8 @@
         "@CanIgnoreReturnValue should not be applied to classes as it almost always overmatches (as"
             + " it applies to constructors and all methods), and the CIRVness isn't conferred to"
             + " its subclasses.",
+    documentSuppression = false,
+    suppressionAnnotations = {},
     severity = ERROR)
 public final class NoCanIgnoreReturnValueOnClasses extends BugChecker implements ClassTreeMatcher {
   private static final String CRV = "com.google.errorprone.annotations.CheckReturnValue";