<?xml version="1.0" encoding="UTF-8"?>
<response>
	<customfields>
		<customfield>
			<privateName>privatename</privateName>
			<publicName>tetet</publicName>
			<displayToUser>1</displayToUser>
			<fieldType>text</fieldType>
			<customFieldId>privatename</customFieldId>
		</customfield>
	</customfields>
</response>

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "response")
public class Response<T> {

    @XmlAnyElement(lax = true)
    private T content;

    public T getContent() {
        return content;
    }

    public void setContent(T content) {
        this.content = content;
    }

}

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "customfields")
public class Customfields {

    @XmlElement(name = "customfield")
    private List<Customfield> customfields;

    public List<Customfield> getCustomfields() {
        return customfields;
    }

    public void setCustomfields(List<Customfield> customfields) {
        this.customfields = customfields;
    }

}

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "customfield")
public class Customfield {

    private String customFieldId;
    private String privateName;

Response<Customfields> response = requestBuilder.post(MediaType.APPLICATION_XML, new GenericType<Response<Customfields>>(){}, customfield);