code: public void loadProvidedPropertiesIfAvailable(File providedPropertiesFile, boolean replaceAllProperties) throws MojoExecutionException {
          if (providedPropertiesFile.exists()) {
              Properties providedPropertySet = loadPropertiesFile(providedPropertiesFile);
              if (replaceAllProperties) {
                  this.properties = providedPropertySet;
              } else {
                  this.properties.putAll(providedPropertySet);
              }
          }
      }
docs: Check if a file exists.  If it does calculate if we need to merge it with existing properties, or replace all existing properties.
  
  @param providedPropertiesFile A properties file that will be check to see if it exists
  @param replaceAllProperties   If we should replace all properties, or just merge them
  @throws MojoExecutionException MojoExecutionException