Merge pull request lightbend#648 from widgetii/master

Performance fix: added capacity parameter in ArrayLists

Author: havocp

config/src/main/java/com/typesafe/config/impl/ConfigParser.java

@@ -59,7 +59,7 @@ private AbstractConfigValue parseConcatenation(ConfigNodeConcatenation n) {
             if (flavor == ConfigSyntax.JSON)
                 throw new ConfigException.BugOrBroken("Found a concatenation node in JSON");
 
-            List<AbstractConfigValue> values = new ArrayList<AbstractConfigValue>();
+            List<AbstractConfigValue> values = new ArrayList<AbstractConfigValue>(n.children().size());
 
             for (AbstractConfigNode node : n.children()) {
                 AbstractConfigValue v = null;

config/src/main/java/com/typesafe/config/impl/SimpleConfigOrigin.java

@@ -364,7 +364,7 @@ static ConfigOrigin mergeOrigins(Collection<? extends ConfigOrigin> stack) {
             Iterator<? extends ConfigOrigin> i = stack.iterator();
             return mergeTwo((SimpleConfigOrigin) i.next(), (SimpleConfigOrigin) i.next());
         } else {
-            List<SimpleConfigOrigin> remaining = new ArrayList<SimpleConfigOrigin>();
+            List<SimpleConfigOrigin> remaining = new ArrayList<SimpleConfigOrigin>(stack.size());
             for (ConfigOrigin o : stack) {
                 remaining.add((SimpleConfigOrigin) o);
             }