FieldAnnotation field = warning.getPrimaryField();
if (field != null) {
if (DEBUG) {
System.out.println("primary field of " + field + " for " + warning);
}
FieldDescriptor fieldDescriptor = field.toFieldDescriptor();
Collection<BugInstance> warnings = warningsByField.get(fieldDescriptor);
if (warnings == null) {
warnings = new LinkedList<BugInstance>();
warningsByField.put(fieldDescriptor, warnings);