Digital Signature Validation

### Description

Im getting " Attempt to read property "ownerDocument" on null" whenever validate the receipts  signature.

### Reproduce

 AS4 Inbound Pipeline Exception: AS4 Cryptographic Signature Exception: Attempt to read property "ownerDocument" on null

### Expected behavior

1

### Oxalis-AS4 version

```bash
1
```

### JDK version

```bash
1
```

### Additional Info

1