Replace new Date().getTime() with System.getCurrentTimeMillis()

pgpainless-core/src/main/java/org/pgpainless/key/generation/KeyRingBuilder.java

@@ -63,7 +63,7 @@ public class KeyRingBuilder implements KeyRingBuilderInterface<KeyRingBuilder> {
     private final List<KeySpec> subkeySpecs = new ArrayList<>();
     private final Map<String, SelfSignatureSubpackets.Callback> userIds = new LinkedHashMap<>();
     private Passphrase passphrase = Passphrase.emptyPassphrase();
-    private Date expirationDate = new Date(new Date().getTime() + YEAR_IN_SECONDS * 5); // Expiration in 5 yeras
+    private Date expirationDate = new Date(System.currentTimeMillis() + YEAR_IN_SECONDS * 5); // Expiration in 5 yeras
 
     @Override
     public KeyRingBuilder setPrimaryKey(@Nonnull KeySpec keySpec) {

pgpainless-core/src/test/java/investigations/TimeTest.java

@@ -0,0 +1,26 @@
+// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package investigations;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+import static org.junit.JUtils.assertEquals;
+
+/**
+ * Exploratory test for date and time related operations.
+ */
+public class TimeTest {
+
+    @Test
+    public void newDateGetTimeEqualsSystemCurrentTimeMillis() {
+        Date date = new Date();
+        long dateTime = date.getTime();
+        long currentTime = System.currentTimeMillis();
+
+        assertEquals(dateTime, currentTime, 10);
+    }
+}