Use contains instead of startsWith for context tab completions

common/src/main/java/me/lucko/luckperms/common/command/tabcomplete/CompletionSupplier.java

@@ -49,6 +49,18 @@ public interface CompletionSupplier {
         return partial -> stringsSupplier.get().filter(TabCompleter.startsWithIgnoreCase(partial)).collect(Collectors.toList());
     }
 
+    static CompletionSupplier contains(String... strings) {
+        return contains(() -> Arrays.stream(strings));
+    }
+
+    static CompletionSupplier contains(Collection<String> strings) {
+        return contains(strings::stream);
+    }
+
+    static CompletionSupplier contains(Supplier<Stream<String>> stringsSupplier) {
+        return partial -> stringsSupplier.get().filter(TabCompleter.containsIgnoreCase(partial)).collect(Collectors.toList());
+    }
+
     List<String> supplyCompletions(String partial);
 
 }

common/src/main/java/me/lucko/luckperms/common/command/tabcomplete/TabCompleter.java

@@ -107,4 +107,13 @@ public class TabCompleter {
         };
     }
 
+    static Predicate<String> containsIgnoreCase(String substring) {
+        return string -> {
+            if (string.length() < substring.length()) {
+                return false;
+            }
+            return string.toLowerCase().contains(substring.toLowerCase());
+        };
+    }
+
 }

common/src/main/java/me/lucko/luckperms/common/command/tabcomplete/TabCompletions.java

@@ -99,7 +99,7 @@ public final class TabCompletions {
             int index = partial.indexOf('=');
             if (index == -1) {
                 // cursor is specifying the key
-                return CompletionSupplier.startsWith(potentialContexts.toMap().keySet()).supplyCompletions(partial);
+                return CompletionSupplier.contains(potentialContexts.toMap().keySet()).supplyCompletions(partial);
             }
 
             // cursor is specifying the value