Thanks a lot @dkayiwa and @darius. @darius I want to achieve the openmrs logo override one time, automatically if I could call it that, whenever I start a new instance.
@dkayiwa, I have tried your suggestion but it didn't work. Now let me be detailed about what I did. I created a package in the omod section of openmrs-module-mapperoverridedemo (which I forked on github): src/main/org/openmrs/modules/mapperoverridedemo/overrideadminpage. And there I put the class CopyLegacyUiContentToWebInf.java. After doing this, building and dropping the omod file in the modules directory of my instance, I got the same result; old logo still present. I still want to get this to work. I really need help to do it right.
Also, what I was asking is if I could use a json file like the one below which @darius pointed out to me a while back, and which was useful in overriding the other logos:
where the id, and extensionPointId have values required to change the admin Logo.
I will continue to explore all the means until I get success. Thanks