fix(build): bind Maven Wrapper distribution to reviewed SHA-256

.mvn/wrapper/maven-wrapper.properties

@@ -1,3 +1,4 @@
 wrapperVersion=3.3.4
 distributionType=only-script
 distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.11/apache-maven-3.9.11-bin.zip
+distributionSha256Sum=0d7125e8c91097b36edb990ea5934e6c68b4440eef4ea96510a0f6815e7eeadb

etl-service/src/test/java/com/xtrmetl/etl/documentation/MavenWrapperIntegrityTest.java

@@ -0,0 +1,96 @@
+package com.xtrmetl.etl.documentation;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Properties;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Prevents Maven Wrapper bootstrap from executing an unverified Maven distribution.
+ *
+ * <p>The wrapper downloads Maven before project compilation and tests can run. This repository
+ * therefore treats the Maven distribution URL and its reviewed SHA-256 as one atomic build-input
+ * contract. A Maven version or URL change must carry a newly reviewed checksum in the same change;
+ * deleting the checksum must fail deterministically without network access.</p>
+ */
+class MavenWrapperIntegrityTest {
+
+    private static final String REVIEWED_DISTRIBUTION_URL =
+            "https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.11/"
+                    + "apache-maven-3.9.11-bin.zip";
+    private static final String REVIEWED_DISTRIBUTION_SHA256 =
+            "0d7125e8c91097b36edb990ea5934e6c68b4440eef4ea96510a0f6815e7eeadb";
+
+    /**
+     * Requires the fixed Maven 3.9.11 download to remain bound to its reviewed SHA-256 checksum.
+     *
+     * @throws IOException when the wrapper properties cannot be read as repository source
+     */
+    @Test
+    void bindsMavenDistributionUrlToReviewedSha256() throws IOException {
+        Properties properties = new Properties();
+        Path wrapperProperties = projectRoot().resolve(
+                ".mvn/wrapper/maven-wrapper.properties"
+        );
+        assertTrue(Files.isRegularFile(wrapperProperties), "Maven Wrapper properties must exist");
+
+        try (Reader reader = Files.newBufferedReader(wrapperProperties, StandardCharsets.UTF_8)) {
+            properties.load(reader);
+        }
+
+        assertEquals("3.3.4", properties.getProperty("wrapperVersion"));
+        assertEquals("only-script", properties.getProperty("distributionType"));
+        assertEquals(
+                REVIEWED_DISTRIBUTION_URL,
+                properties.getProperty("distributionUrl"),
+                "Changing the Maven distribution requires review of a matching checksum"
+        );
+
+        String distributionSha256 = properties.getProperty("distributionSha256Sum");
+        assertNotNull(
+                distributionSha256,
+                "Maven Wrapper must verify the downloaded Maven distribution with SHA-256"
+        );
+        assertTrue(
+                distributionSha256.matches("[0-9a-f]{64}"),
+                "distributionSha256Sum must be 64 lowercase hexadecimal characters"
+        );
+        assertEquals(
+                REVIEWED_DISTRIBUTION_SHA256,
+                distributionSha256,
+                "The checksum must match the reviewed Maven 3.9.11 distribution"
+        );
+    }
+
+    /**
+     * Finds the repository root from reactor-root or module-local Maven execution.
+     *
+     * @return absolute repository root containing the wrapper configuration
+     */
+    private static Path projectRoot() {
+        Path current = Paths.get(System.getProperty("user.dir")).toAbsolutePath();
+        Path lastPomParent = null;
+        while (current != null) {
+            if (Files.exists(current.resolve(".git"))) {
+                return current;
+            }
+            if (Files.exists(current.resolve("pom.xml"))) {
+                lastPomParent = current;
+            }
+            current = current.getParent();
+        }
+        if (lastPomParent != null) {
+            return lastPomParent;
+        }
+        throw new IllegalStateException("Could not find project root");
+    }
+}