Iss #89 - Replace regex in commons to address vulnerable regex

Sonar reported that the regex for checking the page is vulnerable to backtracking attacks, so it was removed. In it's place, we added a helper to parse parameters in a query string.

The previous solution of having a regex helper was very expensive computationally, and didn't fully address the issue, so it was discarded.

core/src/main/java/org/eclipsefoundation/core/helper/ParameterHelper.java

@@ -15,11 +15,13 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map.Entry;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import javax.annotation.PostConstruct;
 import javax.enterprise.context.ApplicationScoped;
 import javax.enterprise.inject.Instance;
 import javax.inject.Inject;
+import javax.ws.rs.core.MultivaluedHashMap;
 import javax.ws.rs.core.MultivaluedMap;
 
 import org.eclipsefoundation.core.namespace.UrlParameterNamespace;
@@ -74,6 +76,23 @@ public class ParameterHelper {
                 }, MultivaluedMapImpl<String, String>::new));
     }
 
+    /**
+     * Parses a decoded query string to create a query map for use in lookups.
+     * 
+     * @param query the decoded query string for a request
+     * @return map of param names to the associated values
+     */
+    public static MultivaluedMap<String, String> parseQueryString(String query) {
+        if (query == null) {
+            return new MultivaluedHashMap<>();
+        }
+        return Stream
+                .of(query.split("&"))
+                .map(q -> q.split("=", 2))
+                .filter(a -> a.length == 2)
+                .collect(MultivaluedHashMap::new, (multimap, input) -> multimap.add(input[0], input[1]), MultivaluedMap::putAll);
+    }
+
     /**
      * Returns a list of parameter names, as generated from reading in the parameters present in the
      * {@link UrlParameterNamespace} implementations.