Merge Java conformance follow-up: origin metatype + loader warnings infra

Issue A — port the origin metatype family to Java (MetaOrigin abstract +
passthrough/aggregate/collection subtypes), accept origin as a child of field.*,
ValidationPhase.validateOrigins enforces @agg vocabulary (ERR_BAD_ATTR_VALUE)
and @via dotted-path traversal through declared relationships (ERR_INVALID_ORIGIN).
Mirrors the TS/C# implementations. Closes 8 conformance ledger entries
(origin-passthrough-simple, origin-aggregate-count, origin-aggregate-sum,
origin-collection-simple, origin-multi-level-via, source-db-view-projection,
error-origin-bad-aggregate-fn, error-origin-bad-via-path).

Issue B — loader warnings surface on MetaDataLoader + missing-primary-identity
warning emitted by ValidationPhase.validateEntityHasPrimaryIdentity.
ConformanceTest honors expected-warnings.json via multiset-equality. Aligns
with TS subtype-rules / C# ValidationPasses (no "has any field" guard — any
concrete entity without primary identity warns). Closes
subtype-entity-missing-primary-warning.

Net: Java conformance ledger 39 → 30 (9 entries closed); ConformanceTest 168/0/0;
metadata 614/0/0; full reactor green.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: dmealing

server/java/metadata/conformance-expected-failures.json

@@ -18,8 +18,6 @@
     "error-extends-nonexistent",
     "error-field-object-storage-flattened-array",
     "error-field-object-storage-no-object-ref",
-    "error-origin-bad-aggregate-fn",
-    "error-origin-bad-via-path",
     "error-parse-malformed-json",
     "error-template-payload-ref-unresolved",
     "error-template-prompt-missing-payload-ref",
@@ -29,14 +27,7 @@
     "extends-cross-file",
     "layout-data-grid-basic",
     "layout-data-grid-multiple-named",
-    "origin-aggregate-count",
-    "origin-aggregate-sum",
-    "origin-collection-simple",
-    "origin-multi-level-via",
-    "origin-passthrough-simple",
     "smoke-empty-metadata",
-    "source-db-view-projection",
-    "subtype-entity-missing-primary-warning",
     "template-output-and-prompt",
     "template-prompt-simple",
     "warning-filterable-no-index"

server/java/metadata/src/main/java/com/metaobjects/field/MetaField.java

@@ -13,6 +13,7 @@
 import com.metaobjects.constraint.PlacementConstraint;
 import com.metaobjects.constraint.RegexConstraint;
 import com.metaobjects.util.DataConverter;
+import com.metaobjects.origin.MetaOrigin;
 import com.metaobjects.validator.MetaValidator;
 import com.metaobjects.validator.MetaValidatorNotFoundException;
 import com.metaobjects.view.MetaView;
@@ -120,10 +121,11 @@ public static void registerTypes(MetaDataRegistry registry) {
             registry.registerType(MetaField.class, def -> {
                 def.type(TYPE_FIELD).subType(SUBTYPE_BASE)
                    .description("Base field metadata with common field attributes")
-                   // ACCEPTS ANY ATTRIBUTES, VALIDATORS AND VIEWS (all field types inherit these)
+                   // ACCEPTS ANY ATTRIBUTES, VALIDATORS, VIEWS, AND ORIGINS (all field types inherit these)
                    .optionalChild(MetaAttribute.TYPE_ATTR, "*")
                    .optionalChild(MetaValidator.TYPE_VALIDATOR, "*")
-                   .optionalChild(MetaView.TYPE_VIEW, "*");
+                   .optionalChild(MetaView.TYPE_VIEW, "*")
+                   .optionalChild(MetaOrigin.TYPE_ORIGIN, "*");
 
                 // FIELD-SPECIFIC ATTRIBUTES WITH FLUENT CONSTRAINTS
                 def.optionalAttributeWithConstraints(ATTR_IS_ABSTRACT)

server/java/metadata/src/main/java/com/metaobjects/loader/MetaDataLoader.java

@@ -28,6 +28,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
@@ -111,6 +112,21 @@ public class MetaDataLoader implements LoaderConfigurable {
     // If set before init(), sources are loaded automatically during init().
     private List<URI> sourceURIs = null;
 
+    // Validation-phase warnings accumulator.
+    //
+    // Mirrors the TS/C#/Python warning surfaces (a per-load list of human-readable
+    // warning strings produced by {@link ValidationPhase}). Consumers — primarily
+    // the conformance harness today — read this after {@link #load(List)} returns
+    // (which is the call site that runs {@link ValidationPhase#run(MetaRoot)}).
+    //
+    // Cleared at the start of every {@link #load(List)} so a subsequent load on
+    // the same loader does not accumulate prior-batch warnings. Errors continue
+    // to be eager-thrown — warnings are non-fatal, errors are not.
+    //
+    // Package-private mutator ({@link #addWarning(String)}) keeps callers
+    // restricted to the loader package (where {@link ValidationPhase} lives).
+    private final List<String> warnings = new ArrayList<>();
+
     /**
      * Convenience constructor accepting only a name.
      * Uses {@link LoaderOptions} defaults (no-register, non-verbose, strict) and
@@ -245,6 +261,46 @@ public MetaDataLoader getLoader() {
         return this;
     }
 
+    ///////////////////////////////////////////////////////////////////////
+    // Validation warnings (cross-language warning surface)
+
+    /**
+     * Returns the validation warnings produced by the most recent {@link #load(List)}
+     * call (or accumulated across multiple loads in this batch). The list is reset
+     * at the start of every {@link #load(List)} invocation.
+     *
+     * <p>Warnings are non-fatal advisory messages emitted by {@link ValidationPhase}.
+     * Errors continue to be eager-thrown — only warnings accumulate here.</p>
+     *
+     * <p>Mirrors the TS/C#/Python warning surfaces; the canonical consumer is the
+     * conformance harness comparing against {@code expected-warnings.json}.</p>
+     *
+     * @return an unmodifiable snapshot of the accumulated warnings (never {@code null})
+     */
+    public List<String> getWarnings() {
+        return Collections.unmodifiableList(new ArrayList<>(warnings));
+    }
+
+    /**
+     * Append a validation warning. Package-private — only the loader-package
+     * validation passes ({@link ValidationPhase}) should be calling this.
+     *
+     * @param warning the warning message; ignored when {@code null} or empty
+     */
+    void addWarning(String warning) {
+        if (warning == null || warning.isEmpty()) return;
+        warnings.add(warning);
+    }
+
+    /**
+     * Clear accumulated warnings. Called at the start of {@link #load(List)} so
+     * a fresh batch does not see stale warnings from a prior load on the same
+     * loader instance.
+     */
+    void clearWarnings() {
+        warnings.clear();
+    }
+
     ///////////////////////////////////////////////////////////////////////
     // ClassLoader
 
@@ -805,6 +861,10 @@ public boolean isRegistered() {
     public MetaDataLoader load(List<MetaDataSource> sources) {
         if (sources == null) throw new IllegalArgumentException("sources must not be null");
 
+        // Reset the per-load warning accumulator so callers see only warnings
+        // produced by THIS batch.
+        clearWarnings();
+
         for (MetaDataSource source : sources) {
             String content;
             try {
@@ -830,8 +890,10 @@ public MetaDataLoader load(List<MetaDataSource> sources) {
 
         // Run post-load validation passes after all sources in this batch are parsed.
         // Fires both when called from init() (via loadSourceURIsIfPresent) and when
-        // called directly by tests or the conformance runner.
-        ValidationPhase.run(root);
+        // called directly by tests or the conformance runner. The loader handle is
+        // passed so non-fatal validation findings can be recorded via
+        // {@link #addWarning(String)} (errors continue to be eager-thrown).
+        ValidationPhase.run(root, this);
 
         return this;
     }