comment improvements

Author: msridhar

nullaway/src/main/java/com/uber/nullaway/generics/GenericsChecks.java

@@ -814,6 +814,8 @@ && isAssignmentToField(tree)) {
                 state.withPath(pathToRhs),
                 (MethodInvocationTree) rhsTree,
                 pathToRhs,
+                // if a local is declared using `var`, don't use its javac-inferred type as part of
+                // inference
                 varLocalDeclaration ? null : lhsType,
                 assignedToLocal,
                 false);
@@ -823,6 +825,7 @@ && isAssignmentToField(tree)) {
         VariableTree varTree = (VariableTree) tree;
         Symbol symbol = ASTHelpers.getSymbol(varTree);
         if (symbol != null) {
+          // if declared with `var` we should always get a non-null VarLocalKey for the symbol
           VarLocalKey key = castToNonNull(getVarLocalKey(symbol));
           inferredVarLocalTypes.put(key, rhsType);
         }

nullaway/src/test/java/com/uber/nullaway/jspecify/VarDeclaredLocalTests.java

@@ -51,6 +51,7 @@ public void varInTryWithResources() {
             @NullMarked
             class Test {
               void test(Iterator<@Nullable Object> iterator) {
+                // just testing that we don't crash here
                 try (var stream = StreamSupport.stream(
                   Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false)) {
                 }