LEGLINK-969: Validation: fetchValueSet requests full ValueSet expansions with _summary=false, transferring hundreds of thousands of concepts per bundle (#1834)

Fetch value sets in summary mode

Co-authored-by: John Britton <johnbritton@users.noreply.github.com>

Author: smailliwcs

Java/validation/src/main/java/com/lantanagroup/link/validation/providers/RemoteTermServiceValidation.java

@@ -261,9 +261,26 @@ private IValidationSupport.ConceptDesignation createConceptDesignation(org.hl7.f
         return conceptDesignation;
     }
 
+    /**
+     * Summary mode used when HAPI asks us to resolve a bound ValueSet.
+     * <p>
+     * Deliberately {@link SummaryEnum#TRUE}: {@code _summary=false} is the condition that makes the Link
+     * terminology service enumerate every code of the value set into {@code ValueSet.expansion.contains}
+     * (see {@code Terminology/Services/FhirService.cs}), which for large value sets is the client-side
+     * trigger for terminology-service memory exhaustion. The expansion is not read by this class -- when
+     * the resolved ValueSet carries a canonical URL, {@link #validateCodeInValueSet} uses only that URL and
+     * routes validation through {@code $validate-code}. The Link terminology service's summary handling is
+     * bespoke rather than element-filtering: at {@code _summary=true} it still returns the stored ValueSet
+     * with its {@code compose} intact, so downstream chain members (e.g. HAPI's in-memory terminology
+     * support) can still expand it in-process.
+     * <p>
+     * Change this only with before/after comparison of validation results -- see
+     * {@code RemoteTermServiceValidationTest#fetchValueSet_requestsSummaryModeTrue}.
+     */
+    static final SummaryEnum FETCH_VALUE_SET_SUMMARY_MODE = SummaryEnum.TRUE;
+
     public IBaseResource fetchValueSet(String theValueSetUrl) {
-        SummaryEnum summaryParam = SummaryEnum.FALSE;
-        return this.fetchValueSet(theValueSetUrl, summaryParam);
+        return this.fetchValueSet(theValueSetUrl, FETCH_VALUE_SET_SUMMARY_MODE);
     }
 
     @Nullable

Java/validation/src/test/java/com/lantanagroup/link/validation/providers/RemoteTermServiceValidationTest.java

@@ -3,14 +3,20 @@
 import ca.uhn.fhir.context.FhirContext;
 import ca.uhn.fhir.context.support.IValidationSupport.CodeValidationResult;
 import ca.uhn.fhir.context.support.IValidationSupport.IssueSeverity;
+import ca.uhn.fhir.rest.api.SummaryEnum;
 import ca.uhn.fhir.rest.client.api.IGenericClient;
+import ca.uhn.fhir.rest.gclient.ICriterion;
 import ca.uhn.fhir.rest.gclient.IOperation;
 import ca.uhn.fhir.rest.gclient.IOperationUnnamed;
 import ca.uhn.fhir.rest.gclient.IOperationUntyped;
 import ca.uhn.fhir.rest.gclient.IOperationUntypedWithInputAndPartialOutput;
+import ca.uhn.fhir.rest.gclient.IQuery;
+import ca.uhn.fhir.rest.gclient.IUntypedQuery;
 import ca.uhn.fhir.rest.server.exceptions.InvalidRequestException;
 import ca.uhn.fhir.rest.server.exceptions.ResourceNotFoundException;
 import com.lantanagroup.link.shared.utils.LogUtils;
+import org.hl7.fhir.instance.model.api.IBaseBundle;
+import org.hl7.fhir.instance.model.api.IBaseResource;
 import org.hl7.fhir.r4.model.*;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
@@ -66,6 +72,34 @@ private IOperation stubClientChain(RemoteTermServiceValidation subject, Object e
         return operation;
     }
 
+    /**
+     * Stubs the fluent {@code client.search().forResource(..).where(..).summaryMode(..).returnBundle(..).execute()}
+     * chain so that {@code execute()} returns the supplied bundle. Returns the query mock so callers can capture
+     * the summary mode requested.
+     */
+    @SuppressWarnings({"rawtypes", "unchecked"})
+    private IQuery stubSearchChain(RemoteTermServiceValidation subject, IBaseBundle executeResult) {
+        IGenericClient client = mock(IGenericClient.class);
+        IUntypedQuery untypedQuery = mock(IUntypedQuery.class);
+        IQuery query = mock(IQuery.class);
+
+        doReturn(client).when(subject).provideClient();
+        when(client.search()).thenReturn(untypedQuery);
+        when(untypedQuery.forResource(anyString())).thenReturn(query);
+        when(query.where(any(ICriterion.class))).thenReturn(query);
+        when(query.summaryMode(any(SummaryEnum.class))).thenReturn(query);
+        when(query.returnBundle(any(Class.class))).thenReturn(query);
+        when(query.execute()).thenReturn(executeResult);
+        return query;
+    }
+
+    private Bundle searchsetContaining(Resource resource) {
+        Bundle bundle = new Bundle();
+        bundle.setType(Bundle.BundleType.SEARCHSET);
+        bundle.addEntry().setResource(resource);
+        return bundle;
+    }
+
     private Parameters validateCodeResponse(boolean result, String paramName, String paramValue) {
         Parameters params = new Parameters();
         params.addParameter().setName("result").setValue(new BooleanType(result));
@@ -298,6 +332,56 @@ void validateCodeInValueSet_withoutCanonicalUrl_sendsValueSetInlineAndDetectsIna
         verify(operation).onType("ValueSet");
     }
 
+    // ---------- fetchValueSet summary mode ----------
+    // fetchValueSet(String) is the public IValidationSupport hook HAPI calls to resolve a bound ValueSet.
+    // Requesting _summary=false makes the Link terminology service enumerate every code of the value set
+    // into ValueSet.expansion.contains, which is the client-side trigger for terminology-service memory
+    // exhaustion -- and the expansion is never read (validateCodeInValueSet uses only the canonical URL).
+    // These tests pin the summary mode so it cannot be silently changed back.
+
+    @Test
+    @SuppressWarnings("rawtypes")
+    void fetchValueSet_requestsSummaryModeTrue() {
+        RemoteTermServiceValidation subject = newSpy();
+        ValueSet valueSet = new ValueSet();
+        valueSet.setUrl(VALUE_SET_URL);
+        IQuery query = stubSearchChain(subject, searchsetContaining(valueSet));
+
+        IBaseResource result = subject.fetchValueSet(VALUE_SET_URL);
+
+        ArgumentCaptor<SummaryEnum> summaryMode = ArgumentCaptor.forClass(SummaryEnum.class);
+        verify(query).summaryMode(summaryMode.capture());
+        assertEquals(SummaryEnum.TRUE, summaryMode.getValue(),
+                "fetchValueSet must not request _summary=false: that makes the terminology service "
+                        + "enumerate the full expansion for a resource whose expansion is never read.");
+        assertSame(valueSet, result);
+    }
+
+    @Test
+    @SuppressWarnings("rawtypes")
+    void fetchValueSet_noMatch_returnsNull() {
+        RemoteTermServiceValidation subject = newSpy();
+        Bundle empty = new Bundle();
+        empty.setType(Bundle.BundleType.SEARCHSET);
+        IQuery query = stubSearchChain(subject, empty);
+
+        assertNull(subject.fetchValueSet(VALUE_SET_URL));
+        verify(query).summaryMode(SummaryEnum.TRUE);
+    }
+
+    @Test
+    @SuppressWarnings("rawtypes")
+    void invokeIsValueSetSupported_requestsSummaryModeTrue() {
+        // The existence check has always used _summary=true; fetchValueSet(String) now matches it.
+        RemoteTermServiceValidation subject = newSpy();
+        ValueSet valueSet = new ValueSet();
+        valueSet.setUrl(VALUE_SET_URL);
+        IQuery query = stubSearchChain(subject, searchsetContaining(valueSet));
+
+        assertTrue(subject.invokeIsValueSetSupported(VALUE_SET_URL));
+        verify(query).summaryMode(SummaryEnum.TRUE);
+    }
+
     // ---------- isCodeSystemSupported / isValueSetSupported delegation to cache ----------
     // These methods are hit per-system per-chain-traversal by HAPI's ValidationSupportChain, so the
     // remote lookup has to go through ValidationCacheService. The tests below verify the delegation