public static Function getFunction(String functionId) {
    return getFunctionExecutionService().getFunction(functionId);
  }
Returns the {@link Function} defined by the functionId, returns null if no function is found
for the specified functionId

@param functionId a functionId
@return the {@link Function} defined by the functionId or null if no function is found for the
        specified functionId

@throws FunctionException if functionID passed is null
@since GemFire 6.0
geode-core/src/main/java/org/apache/geode/cache/execute/FunctionService.java