code: public static function findTypesThatChangedKind(
          Schema $schemaA,
          Schema $schemaB
      ) : iterable {
          $schemaATypeMap = $schemaA->getTypeMap();
          $schemaBTypeMap = $schemaB->getTypeMap();
  
          $breakingChanges = [];
          foreach ($schemaATypeMap as $typeName => $schemaAType) {
              if (! isset($schemaBTypeMap[$typeName])) {
                  continue;
              }
              $schemaBType = $schemaBTypeMap[$typeName];
              if ($schemaAType instanceof $schemaBType) {
                  continue;
              }
  
              if ($schemaBType instanceof $schemaAType) {
                  continue;
              }
  
              $schemaATypeKindName = self::typeKindName($schemaAType);
              $schemaBTypeKindName = self::typeKindName($schemaBType);
              $breakingChanges[]   = [
                  'type'        => self::BREAKING_CHANGE_TYPE_CHANGED_KIND,
                  'description' => "${typeName} changed from ${schemaATypeKindName} to ${schemaBTypeKindName}.",
              ];
          }
  
          return $breakingChanges;
      }
docs: Given two schemas, returns an Array containing descriptions of any breaking
  changes in the newSchema related to changing the type of a type.
  
  @return string[][]