For type variables, read bounds from the corresponding type parameter.

This doesn't matter with the current version of the checker, but it will
keep
[this test](https://github.com/jspecify/jspecify/blob/7b7ff42735cc7be39cc7c862121fb7b14853cfcf/samples/NullExclusiveAtomicReferenceNoArg.java#L92)
passing after we merge the upstream implementation of capture
conversion.

src/main/java/com/google/jspecify/nullness/NullSpecAnnotatedTypeFactory.java

@@ -580,6 +580,27 @@ private boolean nullnessEstablishingPathExists(
   }
 
   private List<? extends AnnotatedTypeMirror> getUpperBounds(AnnotatedTypeMirror type) {
+    /*
+     * In the case of a type-variable usage, we ignore the bounds attached to it in favor of the
+     * bounds on the type-parameter declaration. This will become necessary (in certain cases) after
+     * we merge the upstream implementation of capture conversion.
+     *
+     * I won't claim to understand *why* it will be necessary. Maybe the bounds aren't getting
+     * copied from the declaration to the usage correctly. Or maybe they're getting copied but then
+     * CF is mutating/replacing them (since it seems to update *bounds* based on annotations on the
+     * *usage* in some cases -- though we've tried to short-circuit that).
+     *
+     * In any case, in our model for nullness checking, we always want to look at the original
+     * bounds. So whatever the reason we have different bounds here, we don't want them.
+     *
+     * My only worry is that I always worry about making calls to getAnnotatedType, as discussed in
+     * various comments in this file (e.g., in NullSpecTreeAnnotator.visitMethodInvocation).
+     */
+    if (type instanceof AnnotatedTypeVariable && !isCaptured(type.getUnderlyingType())) {
+      AnnotatedTypeVariable variable = (AnnotatedTypeVariable) type;
+      type = getAnnotatedType(variable.getUnderlyingType().asElement());
+    }
+
     switch (type.getKind()) {
       case INTERSECTION:
         return ((AnnotatedIntersectionType) type).getBounds();