fix(common): add guards to prevent wrapping single collection values...

...again in another collection in HashMapOptions

Author: cmark

commons/com.b2international.commons/src/com/b2international/commons/options/HashMapOptions.java

@@ -130,7 +130,7 @@ public <T> T get(Enum<?> key, Class<T> expectedType) {
 	@SuppressWarnings("unchecked")
 	public final <T> Collection<T> getCollection(String key, Class<T> type) {
 		final Object value = get(key);
-		if (type.isInstance(value)) {
+		if (type.isInstance(value) && (value != null && !Collection.class.isAssignableFrom(value.getClass()))) {
 			return Collections.singleton(type.cast(value));
 		} else {
 			final Collection<Object> collection = get(key, Collection.class);
@@ -154,7 +154,7 @@ public <T> Collection<T> getCollection(Enum<?> key, Class<T> type) {
 	@SuppressWarnings("unchecked")
 	public final <T> Set<T> getSet(String key, Class<T> type) {
 		final Object value = get(key);
-		if (type.isInstance(value)) {
+		if (type.isInstance(value) && (value != null && !Set.class.isAssignableFrom(value.getClass()))) {
 			return Collections.singleton(type.cast(value));
 		} else {
 			final Set<Object> set = get(key, Set.class);
@@ -178,7 +178,7 @@ public <T> Set<T> getSet(Enum<?> key, Class<T> type) {
 	@SuppressWarnings("unchecked")
 	public final <T> List<T> getList(String key, Class<T> type) {
 		final Object value = get(key);
-		if (type.isInstance(value)) {
+		if (type.isInstance(value) && (value != null && !List.class.isAssignableFrom(value.getClass()))) {
 			return Collections.singletonList(type.cast(value));
 		} else {
 			final List<Object> list = get(key, List.class);