GEODE-6557:Handling a possible null situation.

	* There is a possibility that type can be null, which is handled in the return statement.
	* Similar checks were placed in the logger trace statement.

geode-web/src/main/java/org/apache/geode/management/internal/web/http/converter/ServerSerializableObjectHttpMessageConverter.java

@@ -62,7 +62,8 @@ public ServerSerializableObjectHttpMessageConverter() {
   @Override
   protected boolean supports(final Class<?> type) {
     if (logger.isTraceEnabled()) {
-      logger.trace(String.format("%1$s.supports(%2$s)", getClass().getName(), type.getName()),
+      logger.trace(String.format("%1$s.supports(%2$s)", getClass().getName(),
+          type == null ? null : type.getName()),
           new Throwable());
     }