Generate does not remember custom additions to the schema

[aflatoon2874]

• Problem:
  Please note that re-generation of the schema does not remember any custom additions done to the old schema file.
  For example, in the following fragment minimum and maximum attributes have been added manually.

...
"noOfLicenses": {
  "type": "Integer",
  "minimum: 0,
  "maximum": 200
},
...

• Expectation:
  Any custom attributes should be remembered and copied to the new schema file.