code: public final void setPatternPrefix(final String patternPrefix) {
  
          // Check sanity
          validateDiSetterCalledBeforeInitialization("patternPrefix");
  
          // Check sanity
          if (patternPrefix != null) {
  
              // Assign internal state
              this.patternPrefix = patternPrefix;
          } else {
              addDelayedLogMessage("warn", "Received null patternPrefix for configuring AbstractPatternFilter of type ["
                      + getClass().getName() + "]. Ignoring and proceeding.");
          }
      }
docs: Assigns a prefix to be prepended to any patterns submitted to this AbstractPatternFilter.
  
  @param patternPrefix A prefix to be prepended to each pattern to render a Pattern.
  If a null argument is supplied, nothing will be prepended.
  @see #convert(java.util.List, String)