Fix native mode build when jdbc-oracle is combined with jdbc-h2

Fixes native build when `jdbc-oracle` is combined with `jdbc-h2`. This fix was kindly provided Severin Gehwolf and is added as second commit of this PR as 1. integration tests need the fix 2. no point of creating additional integration test module that combines jdbc-oracle and jdbc-h2 as we already have them here.

extensions/jdbc/jdbc-oracle/runtime/src/main/java/io/quarkus/jdbc/oracle/runtime/graal/ObjIdSubstitutions.java

@@ -0,0 +1,44 @@
+package io.quarkus.jdbc.oracle.runtime.graal;
+
+import java.security.SecureRandom;
+
+import com.oracle.svm.core.annotate.Alias;
+import com.oracle.svm.core.annotate.InjectAccessors;
+import com.oracle.svm.core.annotate.TargetClass;
+
+/**
+ * Substitutions required when `jdbc-oracle` is combined with `jdbc-h2`.
+ */
+@TargetClass(className = "java.rmi.server.ObjID")
+public final class ObjIdSubstitutions {
+
+    @Alias
+    @InjectAccessors(SecureRandomAccessor.class)
+    private static SecureRandom secureRandom;
+
+}
+
+class SecureRandomAccessor {
+    private static volatile SecureRandom RANDOM;
+
+    static SecureRandom get() {
+        SecureRandom result = RANDOM;
+        if (result == null) {
+            /* Lazy initialization on first access. */
+            result = initializeOnce();
+        }
+        return result;
+    }
+
+    private static synchronized SecureRandom initializeOnce() {
+        SecureRandom result = RANDOM;
+        if (result != null) {
+            /* Double-checked locking is OK because INSTANCE is volatile. */
+            return result;
+        }
+
+        result = new SecureRandom();
+        RANDOM = result;
+        return result;
+    }
+}