Refine DefaultPersistenceUnitManager substitution predicates

This commit ensures PersistenceException is in the classpath before
applying the substitution (otherwise an error is thrown).

Closes gh-1500

Author: sdeleuze

spring-native/src/main/java/org/springframework/nativex/substitutions/PersistenceExceptionIsAround.java

@@ -0,0 +1,16 @@
+package org.springframework.nativex.substitutions;
+
+import java.util.function.BooleanSupplier;
+
+public class PersistenceExceptionIsAround implements BooleanSupplier {
+
+	@Override
+	public boolean getAsBoolean() {
+		try {
+			Class.forName("javax.persistence.PersistenceException");
+			return true;
+		} catch (ClassNotFoundException e) {
+			return false;
+		}
+	}
+}

spring-native/src/main/java/org/springframework/nativex/substitutions/framework/Target_DefaultPersistenceUnitManager.java

@@ -22,6 +22,7 @@
 import com.oracle.svm.core.annotate.TargetClass;
 
 import org.springframework.nativex.substitutions.OnlyIfPresent;
+import org.springframework.nativex.substitutions.PersistenceExceptionIsAround;
 
 /**
  * Workaround for javax.persistence.PersistenceException: Unable to resolve persistence unit
@@ -30,8 +31,9 @@
  * org.springframework.core.io.ClassPathResource.getURL(ClassPathResource.java:195)
  *
  * @author Andy Clement
+ * @author Sebastien Deleuze
  */
-@TargetClass(className = "org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager", onlyWith = OnlyIfPresent.class)
+@TargetClass(className = "org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager", onlyWith = { OnlyIfPresent.class, PersistenceExceptionIsAround.class })
 final class Target_DefaultPersistenceUnitManager {
 
 	@Substitute