Fix integration tests to properly validate unresolved repository expressions

- Remove premature expression validation from model validator
- Allow expressions to pass through model validation and fail at repository resolution time
- Update integration tests to use dependency:resolve instead of validate to trigger repository usage
- Add -e flag to integration tests to capture suppressed exception messages
- Update test expectations to match the corrected validation flow

The previous approach was rejecting expressions during model validation, but the correct
behavior is to allow expressions to pass through and fail when repositories are actually
used during dependency resolution. This matches the intended design where the MavenValidator
in the resolver catches uninterpolated expressions with the proper error message.

Author: gnodet

impl/maven-impl/src/main/java/org/apache/maven/impl/model/DefaultModelValidator.java

@@ -1590,29 +1590,18 @@ private void validateRawRepository(
         validateStringNotEmpty(
                 prefix, prefix2, "id", problems, Severity.ERROR, Version.V20, repository.getId(), null, repository);
 
-        if (!allowEmptyUrl
-                && validateStringNotEmpty(
-                        prefix,
-                        prefix2,
-                        "[" + repository.getId() + "].url",
-                        problems,
-                        Severity.ERROR,
-                        Version.V20,
-                        repository.getUrl(),
-                        null,
-                        repository)) {
-            // Check for uninterpolated expressions - these should have been interpolated by now
-            Matcher matcher = EXPRESSION_NAME_PATTERN.matcher(repository.getUrl());
-            if (matcher.find()) {
-                addViolation(
-                        problems,
-                        Severity.ERROR,
-                        Version.V40,
-                        prefix + prefix2 + "[" + repository.getId() + "].url",
-                        null,
-                        "contains an uninterpolated expression.",
-                        repository);
-            }
+        if (!allowEmptyUrl) {
+            validateStringNotEmpty(
+                    prefix,
+                    prefix2,
+                    "[" + repository.getId() + "].url",
+                    problems,
+                    Severity.ERROR,
+                    Version.V20,
+                    repository.getUrl(),
+                    null,
+                    repository);
+            // Repository URL interpolation is allowed; unresolved placeholders will fail later during resolution
         }
     }
 

impl/maven-impl/src/test/java/org/apache/maven/impl/model/DefaultModelValidatorTest.java

@@ -895,16 +895,15 @@ void repositoryWithExpression() throws Exception {
     @Test
     void repositoryWithBasedirExpression() throws Exception {
         SimpleProblemCollector result = validateRaw("raw-model/repository-with-basedir-expression.xml");
-        // This test runs on raw model without interpolation, so all expressions appear uninterpolated
-        // In the real flow, supported expressions would be interpolated before validation
-        assertViolations(result, 0, 3, 0);
+        // Repository URL interpolation is allowed; unresolved placeholders will fail later during resolution
+        assertViolations(result, 0, 0, 0);
     }
 
     @Test
     void repositoryWithUnsupportedExpression() throws Exception {
         SimpleProblemCollector result = validateRaw("raw-model/repository-with-unsupported-expression.xml");
-        // Unsupported expressions should cause validation errors
-        assertViolations(result, 0, 1, 0);
+        // Repository URL interpolation is allowed; unresolved placeholders will fail later during resolution
+        assertViolations(result, 0, 0, 0);
     }
 
     @Test

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITgh11140RepoDmUnresolvedTest.java

@@ -37,10 +37,11 @@ void testFailsOnUnresolvedPlaceholders() throws Exception {
         Verifier verifier = newVerifier(testDir.getAbsolutePath());
 
         try {
-            verifier.addCliArgument("validate");
+            verifier.addCliArgument("-e");
+            verifier.addCliArgument("dependency:resolve");
             verifier.execute();
         } catch (VerificationException expected) {
-            // Expected to fail
+            // Expected to fail due to unresolved placeholders reaching repository construction
         }
         // We expect some error mentioning 'Not fully interpolated remote repository' or similar
         verifier.verifyTextInLog("Not fully interpolated remote repository");

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITgh11140RepoInterpolationTest.java

@@ -78,7 +78,8 @@ void testUnresolvedPlaceholderFailsResolution() throws Exception {
         Verifier verifier = newVerifier(testDir.getAbsolutePath());
 
         // Do NOT set env vars, so placeholders stay
-        verifier.addCliArgument("validate");
+        verifier.addCliArgument("-e");
+        verifier.addCliArgument("dependency:resolve");
         try {
             verifier.execute();
         } catch (VerificationException expected) {