CableLabs option (RFC3495): Inconsistent "option_def" usage in client class definitions

Inconsistent "option_def" usage in client class definitions:
Using Kea 2.5.6 - I have yet to try with 2.4.1.

The following "option-def" statement is accepted in the global scope of a
configuration file:

...
        "option-def": [ {
            "name": "Option_122",   "code": 122, "type": "empty", "encapsulate": "Option_122_space" }, {
            "name": "Option_122_1", "code": 1, "space": "Option_122_Space", "type": "ipv4-address" }, {
            "name": "Option_122_2", "code": 2, "space": "Option_122_Space", "type": "ipv4-address" }
    ],
...

However, if this "option-def" is defined within a client class as:

...
       "client-classes": [{
          "name": "Docsis_Class", "test": "substring(option[60].hex,0,6) == 'docsis'",
          "option-def": [ {
            "name": "Option_122",   "code": 122, "type": "empty", "encapsulate": "Option_122_space" }, {
            "name": "Option_122_1", "code": 1, "space": "Option_122_Space", "type": "ipv4-address" }, {
            "name": "Option_122_2", "code": 2, "space": "Option_122_Space", "type": "ipv4-address" }  ],
          "option-data": [ {
            "name": "Option_122_1", "data": "10.0.0.68", "code": 1,  "space": "Option_122_Space" }, {
            "name": "Option_122_2", "data": "10.0.0.69", "code": 2,  "space": "Option_122_Space" } ]
       }],
...

The following message is generated, and Kea exits:

Error encountered: Not allowed option definition for code '122' in space 'dhcp4' 

If the "Option_122" "option-def" is changed to private option "224" as:

...
       "client-classes": [{
          "name": "Docsis_Class", "test": "substring(option[60].hex,0,6) == 'docsis'",
          "option-def": [ {
            "name": "Option_122",   "code": 224, "type": "empty", "encapsulate": "Option_122_space" }, {
            "name": "Option_122_1", "code": 1, "space": "Option_122_Space", "type": "ipv4-address" }, {
            "name": "Option_122_2", "code": 2, "space": "Option_122_Space", "type": "ipv4-address" }  ],
          "option-data": [ {
            "name": "Option_122_1", "data": "10.0.0.68", "code": 1,  "space": "Option_122_Space" }, {
            "name": "Option_122_2", "data": "10.0.0.69", "code": 2,  "space": "Option_122_Space" } ]
       }],
...

Then the following error is generated, and Kea exits:

Error encountered: Not allowed option definition for code '1' in space 'Option_122_Space' 

SF00001775 RT 23426