code: private function collectConflictsBetween(
          ValidationContext $context,
          array &$conflicts,
          $parentFieldsAreMutuallyExclusive,
          array $fieldMap1,
          array $fieldMap2
      ) {
          // A field map is a keyed collection, where each key represents a response
          // name and the value at that key is a list of all fields which provide that
          // response name. For any response name which appears in both provided field
          // maps, each field from the first field map must be compared to every field
          // in the second field map to find potential conflicts.
          foreach ($fieldMap1 as $responseName => $fields1) {
              if (! isset($fieldMap2[$responseName])) {
                  continue;
              }
  
              $fields2       = $fieldMap2[$responseName];
              $fields1Length = count($fields1);
              $fields2Length = count($fields2);
              for ($i = 0; $i < $fields1Length; $i++) {
                  for ($j = 0; $j < $fields2Length; $j++) {
                      $conflict = $this->findConflict(
                          $context,
                          $parentFieldsAreMutuallyExclusive,
                          $responseName,
                          $fields1[$i],
                          $fields2[$j]
                      );
                      if (! $conflict) {
                          continue;
                      }
  
                      $conflicts[] = $conflict;
                  }
              }
          }
      }
docs: Collect all Conflicts between two collections of fields. This is similar to,
  but different from the `collectConflictsWithin` function above. This check
  assumes that `collectConflictsWithin` has already been called on each
  provided collection of fields. This is true because this validator traverses
  each individual selection set.
  
  @param mixed[][] $conflicts
  @param bool      $parentFieldsAreMutuallyExclusive
  @param mixed[]   $fieldMap1
  @param mixed[]   $fieldMap2