Can you please tell me what is the current object for transaction rejected and reversed transaction, I think we can add unit tests for these case where when we perform transaction with reversed and rejected transaction it will work.

This Share Account Approval Note logic seems to be duplicated in both tests, i think a helper function can be extracted especially this part

Map<String, Object> approveMap = new HashMap<>();
approveMap.put("note", "Share Account Approval Note");
approveMap.put("dateFormat", "dd MMMM yyyy");
approveMap.put("approvedDate", "01 March 2016");
approveMap.put("locale", "en");
String approve = new Gson().toJson(approveMap);
ShareAccountTransactionHelper.postCommand("approve", ...);

Map<String, Object> activateMap = new HashMap<>();
activateMap.put("dateFormat", "dd MMMM yyyy");
activateMap.put("activatedDate", "01 March 2016");
activateMap.put("locale", "en");
String activateJson = new Gson().toJson(activateMap);
ShareAccountTransactionHelper.postCommand("activate", ...);

for (Map<String, Object> transaction : transactions) {
Map<String, Object> transactionTypeMap = (Map<String, Object>) transaction.get("type");
List dateList = (List) transaction.get("purchasedDate");
Calendar cal = Calendar.getInstance();
cal.set(dateList.get(0), dateList.get(1) - 1, dateList.get(2));
Date date = cal.getTime();
String transactionType = (String) transactionTypeMap.get("code");
String transactionDate = simple.format(date);

if (transactionType.equals(...) && transactionDate.equals(...)) {
    ...
    break;
}

}

Map<String, List<Map<String, Object>>> rejectMap = new HashMap<>();
List<Map<String, Object>> list = new ArrayList<>();
Map<String, Object> idsMap = new HashMap<>();
idsMap.put("id", additionalSharesRequestId);
list.add(idsMap);
rejectMap.put("requestedShares", list);
String rejectJson = new Gson().toJson(rejectMap);
ShareAccountTransactionHelper.postCommand("rejectadditionalshares", ...);

Please filter the account.getShareAccountTransactions() result first and then iterate over them.

Same as above