Incorrect dereference.of.nullable warning in the scope of an enhanced for loop

Nullness checking of Daikon is failing with the following error:

daikon/AnnotateNullable.java:151: warning: [dereference.of.nullable] dereference of possibly-null reference child_rel
          PptTopLevel child = child_rel.child;
                              ^

A workaround is to change one line in daikon/java/daikon/AnnotateNullable.java from

for (PptRelation child_rel : ppt.children) {

to

for (int i = 0; i < ppt.children.size(); i++) {
    PptRelation child_rel = ppt.children.get(i);

This build shows that workaround succeeding. A minimized test case on tern.cs.washington.edu is needed so the root cause can be found and the issue fixed.

Start with daikon/java/daikon/AnnotateNullable.java and the enhanced for loop over ppt.children that produces the dereference.of.nullable warning. Reduce this case to a minimized Java test case, using the linked type-checking build results as a reference, so the root cause can be identified and the warning is fixed.