Modified how the name is calculated for non camel cased enums.

src/main/java/org/gitlab4j/api/utils/JacksonJsonEnumHelper.java

@@ -42,8 +42,12 @@ public class JacksonJsonEnumHelper<E extends Enum<E>> {
             StringBuilder nameBuf = new StringBuilder(chars.length);
             boolean nextCharIsCapitalized = firstLetterCapitalized;
             for (char ch : chars) {
-                if (ch == '_' && camelCased) {
-                    nextCharIsCapitalized = true;
+                if (ch == '_') {
+                    if (camelCased) {
+                        nextCharIsCapitalized = true;
+                    } else {
+                        nameBuf.append(' ');
+                    }
                 } else if (nextCharIsCapitalized) {
                     nextCharIsCapitalized = false;
                     nameBuf.append(Character.toUpperCase(ch));