refactor: Defer anyOf branch-error allocation to the failure path

Author: thced

src/main/java/com/retailsvc/http/validate/DefaultValidator.java

@@ -527,16 +527,20 @@ private Optional<ValidationError> checkAllOf(Object value, List<Schema> parts, S
   }
 
   private Optional<ValidationError> checkAnyOf(Object value, List<Schema> options, String pointer) {
-    List<ValidationError> failures = new ArrayList<>();
+    List<ValidationError> failures = null;
     for (Schema o : options) {
       Optional<ValidationError> result = check(value, o, pointer);
       if (result.isEmpty()) {
         return OK;
       }
+      if (failures == null) {
+        failures = new ArrayList<>(options.size() - 1);
+      }
       failures.add(result.get());
     }
+    List<ValidationError> branches = failures != null ? failures : List.of();
     return Optional.of(
-        new ValidationError(pointer, "anyOf", "did not match any anyOf branch", value, failures));
+        new ValidationError(pointer, "anyOf", "did not match any anyOf branch", value, branches));
   }
 
   private Optional<ValidationError> checkOneOf(Object value, List<Schema> options, String pointer) {
@@ -559,6 +563,8 @@ private Optional<ValidationError> checkOneOf(Object value, List<Schema> options,
             "oneOf",
             "matched " + matched + " of " + options.size() + " oneOf branches",
             value,
+            // Ambiguous match (matched > 1): the non-matching branches' errors are noise — omit
+            // them.
             matched == 0 ? failures : List.of()));
   }
 

src/test/java/com/retailsvc/http/validate/DefaultValidatorDispatchTest.java

@@ -273,4 +273,12 @@ void anyOfNoMatchCapturesEachBranchError() {
                   .containsExactly("minLength", "maxLength");
             });
   }
+
+  @Test
+  void anyOfEmptyOptionsHasNoBranchErrors() {
+    var schema = new AnyOfSchema(List.of(), Map.of());
+    assertThatThrownBy(() -> v.validate("anything", schema, "/v"))
+        .isInstanceOf(ValidationException.class)
+        .satisfies(t -> assertThat(((ValidationException) t).error().branches()).isEmpty());
+  }
 }