fix: lowercase match value

Author: paullegranddc

internal-api/src/main/java/datadog/trace/bootstrap/config/provider/StableConfigParser.java

@@ -112,6 +112,10 @@ private static boolean matchOperator(String value, String operator, List<String>
     }
     value = value.toLowerCase();
     for (String match : matches) {
+      if (match == null) {
+        continue;
+      }
+      matches = match.toLowerCase();
       switch (operator) {
         case "equals":
           return value == match;