Getting StackTraceElement in groovy application - groovy

Question

I have a piece of code that prints the current java file for logging purposes.
final StackTraceElement stackTraceElement = new Throwable().fillInStackTrace().getStackTrace()[2];
final String parentClassName = stackTraceElement.getFileName().replaceAll(".java", "");
final int lineNumber = stackTraceElement.getLineNumber();
I wrote something in groovy that uses the above code to print logs, it works, most of the time, however after couple of runs I'm starting to get NPE
java.lang.NullPointerException
at com.bla.general.util.log.LogUtils.generateLogMessage(LogUtils.java:140)
at com.bla.general.util.log.LogUtils.info(LogUtils.java:67)
at sun.reflect.GeneratedMethodAccessor831.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
at org.codehaus.groovy.runtime.callsite.StaticMetaMethodSite.invoke(StaticMetaMethodSite.java:43)
at org.codehaus.groovy.runtime.callsite.StaticMetaMethodSite.call(StaticMetaMethodSite.java:88)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
at com.bla.AppVersionServiceImpl.getAppVersion(AppVersionServiceImpl.groovy:47)
When the following line is the originator:
LogUtils.info("Trying to get details for device hash ${deviceHash}");
I'm using tomcat and java 1.7 as my stack. After restarting Tomcat things get back to normal.
It's my first endeavor to the dynamic world of JVM. I'll appreciate if you can enlighten me