Fixed test as XML prolog is not written automatically.

src/test/java/org/orekit/files/ccsds/utils/generation/XmlGeneratorTest.java

@@ -53,7 +53,8 @@ public class XmlGeneratorTest {
             generator.writeEntry("KEY_2",    1234567.8,   Unit.parse("n/a"),       false);
             generator.writeEntry("KEY_3",    1234567.8,   Unit.parse("1"),         false);
             generator.writeEntry("LOOOOONG", "1234567.8", null,                    false);
-            Assert.assertEquals("<KEY_1 units=\"km*kg**3/s**0.5\">1234.5678</KEY_1>\n" +
+            Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
+                                "<KEY_1 units=\"km*kg**3/s**0.5\">1234.5678</KEY_1>\n" +
                                 "<KEY_2>1234567.8</KEY_2>\n" +
                                 "<KEY_3>1234567.8</KEY_3>\n" +
                                 "<LOOOOONG>1234567.8</LOOOOONG>\n",
@@ -68,7 +69,8 @@ public class XmlGeneratorTest {
             generator.writeEntry("KEY_1", 0.5 * FastMath.PI, Unit.parse("°"), false);
             generator.writeEntry("KEY_2", FastMath.PI, Unit.parse("◦"), false);
             generator.writeEntry("PERCENT", 0.25, Unit.parse("%"), false);
-            Assert.assertEquals("<KEY_1 units=\"deg\">90.0</KEY_1>\n" +
+            Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
+                                "<KEY_1 units=\"deg\">90.0</KEY_1>\n" +
                                 "<KEY_2 units=\"deg\">180.0</KEY_2>\n" +
                                 "<PERCENT units=\"%\">25.0</PERCENT>\n",
                                 caw.toString());
@@ -81,7 +83,8 @@ public class XmlGeneratorTest {
         try (Generator generator = new XmlGenerator(caw, 2, "", false)) {
             generator.writeEntry("KEY_1", 0.5 * FastMath.PI, Unit.parse("°"), false);
             generator.writeEntry("KEY_2", FastMath.PI, Unit.parse("◦"), true);
-            Assert.assertEquals("<KEY_1>90.0</KEY_1>\n" +
+            Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
+                                "<KEY_1>90.0</KEY_1>\n" +
                                 "<KEY_2>180.0</KEY_2>\n",
                                 caw.toString());
         }