Index: opensaml-core-api/src/main/resources-filtered/org/opensaml/core/version.properties
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/opensaml-core-api/src/main/resources-filtered/org/opensaml/core/version.properties b/opensaml-core-api/src/main/resources-filtered/org/opensaml/core/version.properties
new file mode 100644
--- /dev/null	(date 1787995420086)
+++ b/opensaml-core-api/src/main/resources-filtered/org/opensaml/core/version.properties	(date 1787995420086)
@@ -0,0 +1,3 @@
+# Generated at build time by Maven resource filtering; do not edit.
+# See the "resources-filtered" resource directory declared in opensaml-core-api/pom.xml.
+version=${project.version}
Index: opensaml-core-api/pom.xml
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/opensaml-core-api/pom.xml b/opensaml-core-api/pom.xml
--- a/opensaml-core-api/pom.xml	(revision 0020ffcf6e2e339bb9a07ce8bf23d781c8e33d18)
+++ b/opensaml-core-api/pom.xml	(date 1787995444943)
@@ -54,6 +54,17 @@
     </dependencies>
     
     <build>
+        <resources>
+            <!-- Default resources, which must be redeclared because this module adds a second directory. -->
+            <resource>
+                <directory>src/main/resources</directory>
+            </resource>
+            <!-- Injects the build version into org/opensaml/core/version.properties, read by Version. -->
+            <resource>
+                <directory>src/main/resources-filtered</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
         <plugins>
             <plugin>
                 <artifactId>maven-jar-plugin</artifactId>
Index: opensaml-core-api/src/main/java/org/opensaml/core/Version.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/opensaml-core-api/src/main/java/org/opensaml/core/Version.java b/opensaml-core-api/src/main/java/org/opensaml/core/Version.java
--- a/opensaml-core-api/src/main/java/org/opensaml/core/Version.java	(revision 0020ffcf6e2e339bb9a07ce8bf23d781c8e33d18)
+++ b/opensaml-core-api/src/main/java/org/opensaml/core/Version.java	(date 1787995460169)
@@ -14,13 +14,26 @@
 
 package org.opensaml.core;
 
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Properties;
+
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import net.shibboleth.shared.annotation.constraint.NotEmpty;
+
 /** Class for printing the version of this library. */
 public final class Version {
 
+    /** Build-generated resource carrying the library version. */
+    @Nonnull @NotEmpty private static final String VERSION_RESOURCE = "version.properties";
+
+    /** Name of the property within {@link #VERSION_RESOURCE} holding the version. */
+    @Nonnull @NotEmpty private static final String VERSION_PROPERTY = "version";
+
     /** IdP version. */
-    @Nullable private static final String VERSION = Version.class.getPackage().getImplementationVersion();
+    @Nullable private static final String VERSION = loadVersion();
 
     /** Constructor. */
     private Version() {
@@ -43,5 +56,37 @@
     @Nullable public static String getVersion() {
         return VERSION;
     }
-    
-}
\ No newline at end of file
+
+    /**
+     * Read the library version from the build-generated resource alongside this class.
+     * 
+     * <p>The version cannot be obtained from {@link Package#getImplementationVersion()} alone: a
+     * {@link Package} belonging to a named module never carries the manifest's versioning attributes, so
+     * that method returns null whenever this library is loaded from the module path. The module
+     * descriptor is no substitute either, because for an automatic module its version is derived from
+     * the JAR file name, which is absent or wrong once the JAR is renamed or repackaged.</p>
+     * 
+     * @return version of the library, or null if it cannot be determined
+     */
+    @Nullable private static String loadVersion() {
+        // NOTE: the resource name deliberately has no leading slash, so that it resolves relative to this
+        // class's own package. Unlike a ClassLoader lookup, that keeps the read inside this library's
+        // module when it is loaded from the module path, and picks the right JAR on the class path.
+        try (final InputStream is = Version.class.getResourceAsStream(VERSION_RESOURCE)) {
+            if (is != null) {
+                final Properties props = new Properties();
+                props.load(is);
+                final String version = props.getProperty(VERSION_PROPERTY);
+                if (version != null && !version.isEmpty()) {
+                    return version;
+                }
+            }
+        } catch (final IOException e) {
+            // Ignored, in favour of the class path fallback below.
+        }
+
+        // Only reached if the resource is missing or unreadable, and then only useful on the class path.
+        return Version.class.getPackage().getImplementationVersion();
+    }
+
+}