Address can not contain "&" character

When I try to book something, using this SDK, that has the `&` character in the name, like a company "example GmbH & Co. KG", then I get the following error:

```
DOMDocument::createElement(): unterminated entity reference
```

So that means, all the `createElement` calls that have a value directly given can throw this error.
I build a small demo: https://onlinephp.io?s=s7EvyCjg5eLlUknJT1awVchLLVdw8fd1yU8uzU3NK9HQtAZK5eWnpALlQEp07ZKLUhNLUl1zUsHyShW5OUo6CkoZiTk5-QpqCuWpOSVKYE1gxYkFBal5Kc4ZmTkpGmBjQFKpyRn5UMOKE8tSI3x9gNYAAA%2C%2C&v=8.2.7

I looked though the source code and that way of setting the value of an xml node is used a lot.
All of these have this potential escaping issue.