Problem description: It is allowed to add new value mapping with a symbol that requires esacping in its name, but after the configuration form is submitted, when attempting to update the configuration of this value mapping an "Unexpected server error" is returned in Value mapping configuration dialog.

Furthermore, even though the error is displayed and configuration dialog is still opened, the changes are already saved, and will be applied if You cancel the configuration update.

Steps to reproduce:

1. Open configuration of any existing host
2. Open Value mapping tab
3. Add a value mapping that has double quotes in its name, for exmple: AA"aa
4. Submit Value mapping configuration dialog - notice that value mapping is successfully saved
5. Open configuration of this Value mapping in edit mode
6. Add another symbol to the name of the value mapping (for example letter B)
7. Attempt to save Value mapping configuration

Result:

1. "Unexpected server error" error is displayed
2. Configuration dialog is not closed
3. If You press the Cancel button You will see that the new letter was actually added to the name of the value mapping

Expected: No errors should be observed, configuration form should be submitted, value mapping update should be successful.

Example: