# Optional sequence\ parameters? **URL:** \ **Category:** Forum\ **Tags:** analytics, Streaming-Analytics-Apama\ **Created:** [February 19, 2025, 12:20pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024 "2025-02-19T12:20:40Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Harald\_Meyer](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/harald_meyer/32/1959_2.png) [@Harald\_Meyer](https://community.cumulocity.com/u/Harald_Meyer)\ **Post date:** [February 19, 2025, 12:20pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/1 "2025-02-19T12:20:40Z")
Hi, in a custom block to invoke an HTTP endpoint, we want to give users to option to provide additional headers for the request using a sequence parameter. This should be optional but when activating a model, we get an error about a mandatory parameter missing. We tried using optional\< sequence \> but in that case we only get a single text field instead of an extensible list of name-value fields. My understanding from the documentation is that “optional” should work in this case as well: > Is that a misunderstanding? ---
**Author:** ![Sudha\_Jallu](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/sudha_jallu/32/31978_2.png) [@Sudha\_Jallu](https://community.cumulocity.com/u/Sudha_Jallu)\ **Post date:** [February 19, 2025, 2:42pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/2 "2025-02-19T14:42:29Z")
Hi Herald, Yes, this should work. I have tested with **Range Lookup** block by adding one more parameter **optional\\> testRanges**. I can see it is taking as list. **output of block with new param** test ranges are present [apama.as.NV(“5.0”,any(string,“bla”)),apama.as.NV(“15”,any(string,“blabla”))] Thanks, Sudha Jallu ---
**Author:** ![Harald\_Meyer](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/harald_meyer/32/1959_2.png) [@Harald\_Meyer](https://community.cumulocity.com/u/Harald_Meyer)\ **Post date:** [February 19, 2025, 2:43pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/3 "2025-02-19T14:43:42Z")
ok, let us retest that again. ---
**Author:** ![Marvin\_Fecke](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/marvin_fecke/32/32111_2.png) [@Marvin\_Fecke](https://community.cumulocity.com/u/Marvin_Fecke)\ **Post date:** [February 19, 2025, 3:04pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/4 "2025-02-19T15:04:09Z")
Hi, I tried it again I configured the headers parameter like this ```auto /** * Headers. * * Additional Headers to add. * @$displayType List of Header Key and Header Value * @$displayHeaderName Header Key * @$displayHeaderValue Header Value * @$minNumEntries 0 * */ optional> headers; ``` But the block looks like this: ![image](https://europe1.discourse-cdn.com/flex005/uploads/cumulocity/original/3X/b/e/bee0ef1c23070d494f5a1bb245b679cbf31296f2.png) It looks like an usual text field and not like a sequence for Name Values. ---
**Author:** ![Sudha\_Jallu](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/sudha_jallu/32/31978_2.png) [@Sudha\_Jallu](https://community.cumulocity.com/u/Sudha_Jallu)\ **Post date:** [February 19, 2025, 3:09pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/5 "2025-02-19T15:09:32Z")
Let me try from UI too. ---
**Author:** ![Sudha\_Jallu](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/sudha_jallu/32/31978_2.png) [@Sudha\_Jallu](https://community.cumulocity.com/u/Sudha_Jallu)\ **Post date:** [February 20, 2025, 11:19am UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/6 "2025-02-20T11:19:22Z")
Hi, Yes you are right, It is not allowing from the UI. I will create defect and also see if there is any workaround for this. Thanks, Sudha Jallu. ---
**Author:** ![Sudha\_Jallu](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/sudha_jallu/32/31978_2.png) [@Sudha\_Jallu](https://community.cumulocity.com/u/Sudha_Jallu)\ **Post date:** [February 21, 2025, 12:42pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/7 "2025-02-21T12:42:12Z")
Hi, I’m afraid there is no workaround available. We will get back to you as we investigate further. Could you share the platform details you are using ? Thanks, Sudha Jallu. ---
**Author:** ![Vinod\_Kumar2](https://avatars.discourse-cdn.com/v4/letter/v/b9e5f3/32.png) [@Vinod\_Kumar2](https://community.cumulocity.com/u/Vinod_Kumar2)\ **Post date:** [February 27, 2025, 12:24pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/8 "2025-02-27T12:24:06Z")
Hi Harald, The issue has been fixed, and the fix is now available in the public block-sdk Git repository ( [Cumulocity-IoT/apama-analytics-builder-block-sdk: Apama Analytics Builder Block SDK](https://github.com/Cumulocity-IoT/apama-analytics-builder-block-sdk)) as part of version 26.48.0. Thanks & Regards, Vinod ---
**Author:** ![Marvin\_Fecke](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/marvin_fecke/32/32111_2.png) [@Marvin\_Fecke](https://community.cumulocity.com/u/Marvin_Fecke)\ **Post date:** [February 27, 2025, 2:56pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/9 "2025-02-27T14:56:33Z")
Hi I also tried it and it is looking fine now. Thank you for your help. ---
**Author:** ![Harald\_Meyer](https://dub1.discourse-cdn.com/flex005/user_avatar/community.cumulocity.com/harald_meyer/32/1959_2.png) [@Harald\_Meyer](https://community.cumulocity.com/u/Harald_Meyer)\ **Post date:** [February 28, 2025, 2:57pm UTC](https://community.cumulocity.com/t/optional-sequence-namevalue-parameters/8024/10 "2025-02-28T14:57:16Z")
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