Fabric8's Kubernetes Client is using a generated model and DSL that has the exact same structure as as the JSON and YAML configuration.
So in order to create a Service instance that looks like:
 {
   "kind": "Service",
   "apiVersion": "v1",
   "metadata": {
       "name": "myservice"
   },
   "spec": {
       "ports": [
           {
              "protocol": "TCP",
              "port": 80,
              "targetPort": 8080,
          }
      ],
      "selector": {
          "key": "value1",
      },¬
      "portalIP": "172.30.234.134",
      "type": "ClusterIP",
  }
}
You can use the following code:
Service service = new ServiceBuilder()
          .withNewMetadata()
              .withName("myservice")
          .endMetadata()
          .withNewSpec()
            .addNewPort()
              .withProtocol("TCP")
              .withPort(80)
              .withNewTargetPort(8080)
            .endPort()
            .addToSelector("key1", "value1")
            .withPortalIP("172.30.234.134")
            .withType("ClusterIP")
          .endSpec()
          .build();
If don't need to hold a reference of the service object and you just want to create it, you can inline it like:
client.services().createNew()
          .withNewMetadata()
              .withName("myservice")
          .endMetadata()
          .withNewSpec()
            .addNewPort()
              .withProtocol("TCP")
              .withPort(80)
              .withNewTargetPort(8080)
            .endPort()
            .addToSelector("key1", "value1")
            .withPortalIP("172.30.234.134")
            .withType("ClusterIP")
          .endSpec()
          .done();