Fix bug in ShortTermMemoryHandler with ArrayIndexOutOfBoundsException (#2811)

Author: tzolotuhin

java/server/src/org/openqa/selenium/remote/server/log/ShortTermMemoryHandler.java

@@ -55,7 +55,7 @@ public ShortTermMemoryHandler(int capacity, Level minimumLevel, Formatter format
 
 
   @Override
-  public void publish(LogRecord record) {
+  public synchronized void publish(LogRecord record) {
     if (record.getLevel().intValue() < minimumLevel) {
       return;
     }
@@ -67,12 +67,12 @@ public void publish(LogRecord record) {
   }
 
   @Override
-  public void flush() {
+  public synchronized void flush() {
     /* NOOP */
   }
 
   @Override
-  public void close() throws SecurityException {
+  public synchronized void close() throws SecurityException {
     for (int i = 0; i < capacity; i++) {
       lastRecords[i] = null;
     }
@@ -95,7 +95,7 @@ public synchronized LogRecord[] records() {
     return validRecords.toArray(new LogRecord[validRecords.size()]);
   }
 
-  public String formattedRecords() {
+  public synchronized String formattedRecords() {
     final StringWriter writer;
 
     writer = new StringWriter();