In the case of the RI when a step is partitioned the call

BatchRuntime.getJobOperator().getJobExecution(execID).getJobParameters();

returns the specific partition properties.
Jberet returns the properties passed in the start method.
This causes the example of phonebilling to fail with a NPE (BillReader)

http://docs.oracle.com/javaee/7/tutorial/doc/batch-processing009.htm

output for the maven project attached:
#output with RI
----------------------------------
Batch started: id 1
getPartitionProperties
open()
open()
Job params:

{test=0}

Job properties:

{jobProperty=mytest0.txt}

Step properties:

{stepProperty=mytest0.txt}
Job params: {test=1}
Job properties: {jobProperty=mytest1.txt}
Step properties: {stepProperty=mytest1.txt}

#output with jberet
-----------------------------------
Batch started: id 1
getPartitionProperties
open()
open()
Job params: {parameter2=param2, parameter1=param1}
Job properties: {jobProperty=mytest#{partitionPlan['test']}.txt}
Step properties: {stepProperty=mytest0.txt}

Job params:

{parameter2=param2, parameter1=param1}

Job properties: {jobProperty=mytest#

{partitionPlan['test']}

.txt}
Step properties:

{stepProperty=mytest1.txt}