code: static public String getSourceCodeRelativePathForStackTraceElement(StackTraceElement ste) {
          String packageName = ste.getClassName();
          // e.g. com.fizzed.test.Application$1 for an internal class
          int pos = packageName.lastIndexOf('.');
          if (pos > 0) {
              packageName = packageName.substring(0, pos);
              return
                  packageName.replace(".", File.separator)
                  + File.separator
                  + ste.getFileName();
          } else {
              // must be in default package
              return
                  ste.getFileName();
          }
      }
docs: Calculates the relative path of the source code file of a StackTrace
  element if its available. Uses the packageName of the class to create a relative path
  and appends the "filename" included with the stack trace element.
  @param ste The stack trace element
  @return The relative path of the source code file or null if the information
  wasn't available in the stack trace element.