5.2.6 Backported issues

[fmbenhassine]

• FlowStep sets job status to completed even when there are more pending steps #5381
• NullPointerException in JacksonJsonObjectReader.close() and GsonJsonObjectReader.close() #5281
• appendAllowed(true) breaks JSON array when the writer is opened/written/closed multiple times #5272
• ExecutionContext dirty flag is never cleared #5249
• CompositeItemReader Does Not Reset Iterator for Subsequent Job Executions #4926