Update to errorprone 2.21.1 (#564)

build.gradle

@@ -863,7 +863,7 @@ subprojects {
         //  * Temporarily comment out "-Werror" elsewhere in this file
         //  * Repeatedly run `./gradlew clean compileJava` and fix all errors
         //  * Uncomment "-Werror"
-        ext.errorproneVersion = '2.20.0'
+        ext.errorproneVersion = '2.21.1'
         errorprone group: 'com.google.errorprone', name: 'error_prone_core', version: errorproneVersion
 
         // TODO: it's a bug that annotatedlib:guava requires the error_prone_annotations dependency.

framework/src/main/java/org/checkerframework/common/reflection/DefaultReflectionResolver.java

@@ -525,7 +525,7 @@ private List<Symbol> getMethodSymbolsfor(
         List<Symbol> result = new ArrayList<>();
         ClassSymbol classSym = (ClassSymbol) sym;
         while (classSym != null) {
-            for (Symbol s : classSym.getEnclosedElements()) {
+            for (Symbol s : getEnclosedElements(classSym)) {
                 // check all member methods
                 if (s.getKind() == ElementKind.METHOD) {
                     // Check for method name and number of arguments
@@ -568,11 +568,11 @@ private List<Symbol> getConstructorSymbolsfor(
         }
 
         // TODO: Should this be used instead of the below??
-        ElementFilter.constructorsIn(symClass.getEnclosedElements());
+        ElementFilter.constructorsIn(getEnclosedElements(symClass));
 
         // The common case is probably that there is one constructor of the given parameter length.
         List<Symbol> result = new ArrayList<>(2);
-        for (Symbol s : symClass.getEnclosedElements()) {
+        for (Symbol s : getEnclosedElements(symClass)) {
             // Check all constructors
             if (s.getKind() == ElementKind.CONSTRUCTOR) {
                 // Check for number of parameters
@@ -610,6 +610,18 @@ private Symbol getSymbol(String className, Env<AttrContext> env, Names names, Re
         }
     }
 
+    /**
+     * Determine the enclosed elements for an element. This wrapper is useful to avoid a signature
+     * change in the called method.
+     *
+     * @param sym the element
+     * @return the enclosed elements
+     */
+    @SuppressWarnings("ASTHelpersSuggestions") // Use local helper.
+    private static List<Symbol> getEnclosedElements(Symbol sym) {
+        return sym.getEnclosedElements();
+    }
+
     /**
      * Build lub of the two types (represented by sets {@code set1} and {@code set2}) using the
      * provided AnnotatedTypeFactory.