@Nullable
  public TypeConversionDescriptorBase findConversion(final PsiType from, final PsiType to, final PsiMember member,
                                                     final PsiExpression context, final TypeMigrationLabeler labeler) {
    for (TypeConversionRule descriptor : myConversionRules) {
      final TypeConversionDescriptorBase conversion = descriptor.findConversion(from, to, member, context, labeler);
      if (conversion != null) return conversion;
    }
    return null;
  }
@Nullable
  public TypeConversionDescriptorBase findConversion(final PsiType from, final PsiType to, final PsiMember member,
                                                     final PsiExpression context, final TypeMigrationLabeler labeler)