TCString.encode wrongly sets vendor legitimate interest to false

[sbanerjee97]

Version
1.5.13

Module (core, cmpapi, cli, stub, or testing)
Core
Describe with reproduction steps – What is the expected behavior?
Hello, wanted to ask about expected behaviour and potentially report a bug.
We have for example vendor ID 628 that has purposes, special purposes but no legitimate interest.

When user overrides the vendor config in the CMP to restrict all the purposes for the vendor, then the vendor essentially has no purposes, no legitimate interest but has special purposes.

In such a case our understanding is that legitimate interest for this vendor should be set to true. We are setting this to true and passing it to the 'TCString.encode' function.

But looks like the encode function is returning an encoded TC string that sets vendor legitimate interest for this vendor(628) to false.
Here's the TC String:
CQCm-uQQCm-uQAcABBENA_FsAP_gAEPgAAwIKYtV_G__bWlr8X73aftkeY1P9_h77sQxBhfJE-4FzLuW_JwXx2ExNA36tqIKmRIAu3bBIQNlHJDUTVCgaogVryDMakWcoTNKJ6BkiFMRO2cYCF5vmwtj-QKY5vr993dx2B-t_dr83dzyz4VHn3a5_2a0WJCdA5-tDfv9bROb-9IOd_58v4v0_F_rE2_eT1l_tevp7D9-cts7_XW-9_fff79Ln_-uAAA-Cl4BJhoVEAZZEhIQaBhBAgBUFYQEUCAAAAEgaICAEwYFOwMAl1hIgBACgAGCAEAAKMgAQAACQAIRABAAUCAACAQKAAEACAYCABgYAAwAWAgEAAIDoEKYEECgWACRmREKYEIQCQQEtlQgkAQIK4QhFngQQCImCgAABIAKwABAWCwOJJASsSCBLiDaAAAgAQCCACoRSdmAIIAzZaq8WTaMrSAtHzBc8AAGAMCAAgJ0CAAQE6BgAICdBAAEBOg4ACAnQoABAToA.f_wACHwAAAAA

The question here is when a vendor has no purpose, no legitimate interest but has special purposes - should we not set legitimate interest for the vendor to true?
If we should, it looks like this is a bug from IAB that needs to be fixed.

[HeinzBaumann]

When you reference to user overriding the vendor config. Do you mean the publisher using Publisher restrictions? Or the user within the CMP not allowing any purposes under consent?

In any case, you should not change the setting that the user has made. If the user sets all purposes to no consent and there are no purposes set by the vendor for LI, the LI bits are false. you cannot set the LI bit to true within your CMP. The user choice is no consent and no LI. That is what needs to be written out. The library checks for this and correctly writes out the bits for LI as false or doesn't populate it which means no LI.

[HeinzBaumann]

Addressed with code change, commit #472.
@sbanerjee97