Json Mapping Exception can not deserialize instance out of START_ARRAY token

You have declared parameters as a single object, but you are returning it as an array of multiple objects in your JSON document.

Your model currently defines the parameters node as a ParametersType object:

@JsonProperty( "parameters" )
@XmlElement( required = true )
protected ParametersType parameters;

This means your model object is expecting a JSON document that looks like the following:

{
    "templateId": "123",
    "parameters": {
            "parameter": [
                {
                    "key": "id",
                    "value": "1",
                    "type": "STRING_TYPE"
                },
                {
                    "key": "id2",
                    "value": "12",
                    "type": "STRING_TYPE"
                }
            ]
        },
    "documentFormat": "PDF"
}

But in your JSON document you are returning an array of ParametersType objects. So you need to change your model to be a list of ParametersType objects:

@JsonProperty( "parameters" )
@XmlElement( required = true )
protected List<ParametersType> parameters;

The fact that you are returning an array of ParametersType objects is why the parser is complaining about not being able to deserialize an object out of START_ARRAY. It was looking for a node with a single object, but found an array of objects in your JSON.