Wso2 XACML get custom attributes - wso2

Question

I am using Wso2 IS 5.11.0, I have a requirement where I need to fetch the user attributes by calling web-service based.
Below is the sample attribute finder code:
public class CustomPIPAttributeFinder extends AbstractPIPAttributeFinder {
private static final String PIP_NAME = "CustomPIPAttributeFinder";
private static final Set<String> SUPPORTED_ATTRIBUTES;
private static final Log log = LogFactory.getLog(CustomPIPAttributeFinder.class);
static {
SUPPORTED_ATTRIBUTES = new HashSet<String>();
SUPPORTED_ATTRIBUTES.add(CustomPIPConstants.SAMPLE_ATTRIBUTE_ID);
SUPPORTED_ATTRIBUTES.add(CustomPIPConstants.SAMPLE_ATTRIBUTE_NAME);
SUPPORTED_ATTRIBUTES.add(CustomPIPConstants.SAMPLE_CATEGORY);
}
#Override
public Set<String> getAttributeValues(URI attributeType, URI attributeId, URI category, String issuer,
EvaluationCtx evaluationCtx) throws Exception {
//code
}
private String retrieveSampleName(String accessToken) {
String sampleName = null;
// TODO: Get the value of the sample name from the sampleID from the datasource
return sampleName;
}
/**
* Since we override the {#link #getAttributeValues(URI, URI, URI, String, EvaluationCtx)} this won't be called.
*/
#Override
public Set<String> getAttributeValues(String subject, String resource, String action, String environment,
String attributeId, String issuer) throws Exception {
throw new UnsupportedOperationException("Method unsupported in the context");
}
public void init(Properties properties) throws Exception {
}
public String getModuleName() {
return PIP_NAME;
}
public Set<String> getSupportedAttributes() {
return SUPPORTED_ATTRIBUTES;
}
}
In the sample code we can fetch only one attribute per request.But how can we return multiple attributes before executing policy or get multiple attributes in one request from custom attribute finder. Is there any way to achieve this flow.
As per above code request attribute find(returns only one) in the example it will increase the overhead as for each attribute lookup we are calling web-service every time as it'll increase overhead.