Add a mail session producer using MicroProfil Config API to map to se…

…ssion properties. IQSS#7424

src/main/java/edu/harvard/iq/dataverse/util/MailSessionProducer.java

@@ -0,0 +1,40 @@
+package edu.harvard.iq.dataverse.util;
+
+import org.eclipse.microprofile.config.Config;
+import org.eclipse.microprofile.config.ConfigProvider;
+
+import javax.annotation.Resource;
+import javax.enterprise.inject.Produces;
+import javax.inject.Singleton;
+import javax.mail.Session;
+import java.util.Map;
+import java.util.Properties;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+@Singleton
+public class MailSessionProducer {
+
+    public static final String MAIL_CONFIG_PREFIX = "dataverse.mail.system";
+
+    @Produces
+    @Resource(name = "java:app/notify/mail/system")
+    public Session getSystemMailSession() {
+        return Session.getInstance(getMailProperties());
+    }
+
+    Properties getMailProperties() {
+        Config config = ConfigProvider.getConfig();
+
+        // Map properties 1:1 to mail.smtp properties for the mail session.
+        // See https://javaee.github.io/javamail/docs/api/com/sun/mail/smtp/package-summary.html for an extensive list
+        // of options.
+        Map<String,String> propMap = StreamSupport.stream(config.getPropertyNames().spliterator(), false)
+                                                  .filter(prop -> prop.startsWith(MAIL_CONFIG_PREFIX+"."))
+                                                  .collect(Collectors.toConcurrentMap(s -> s.replace(MAIL_CONFIG_PREFIX, "mail.smtp"), s -> config.getValue(s, String.class)));
+        Properties mailProps = new Properties();
+        mailProps.putAll(propMap);
+
+        return mailProps;
+    }
+}