Fix #29: Resolve code review feedback

Author: Aaron Long

core/src/main/java/com/newrelic/logging/core/ExceptionUtil.java

@@ -25,7 +25,7 @@ public static String getErrorStack(StackTraceElement[] stack, Integer maxStackSi
             return null;
         }
 
-        StringBuilder stackBuilder = new StringBuilder(maxStackSize);
+        StringBuilder stackBuilder = new StringBuilder();
         for(int i = 0; i < Math.min(maxStackSize, stack.length); i++) {
             stackBuilder.append("  at " + stack[i].toString() + "\n");
         }

logback/src/main/java/com/newrelic/logging/logback/NewRelicEncoder.java

@@ -32,7 +32,7 @@
 public class NewRelicEncoder extends EncoderBase<ILoggingEvent> {
     private NewRelicJsonLayout layout;
 
-    Integer maxStackSize = MAX_STACK_SIZE;
+    private Integer maxStackSize = MAX_STACK_SIZE;
 
     @Override
     public byte[] encode(ILoggingEvent event) {
@@ -53,6 +53,10 @@ public void start() {
         layout.start();
     }
 
+    public void setMaxStackSize(final Integer maxStackSize) {
+        this.maxStackSize = maxStackSize;
+    }
+
     @Override
     public byte[] headerBytes() {
         return new byte[0];

logback/src/main/java/com/newrelic/logging/logback/NewRelicJsonLayout.java

@@ -23,7 +23,7 @@
 import static com.newrelic.logging.core.ExceptionUtil.MAX_STACK_SIZE;
 
 public class NewRelicJsonLayout extends LayoutBase<ILoggingEvent> {
-    private Integer maxStackSize;
+    private final Integer maxStackSize;
 
     public NewRelicJsonLayout() {
         this(MAX_STACK_SIZE);