Hi everyone,
I am having a problem with GSEABase package, I am not sure if this is the place where I should post this.
Well, my problem. I am creating a GeneSet with genes, setName and setIdentifier, however, when I update its name I get the setIdentifier automatically modified. Here is my code:

> library(GSEABase);
> # creating a GeneSet with genes "1".."10", name MyName and id MyId
> myGset <- GeneSet(as.character(1:10), setName="MyName", setIdentifier="MyId");
> details(myGset);
setName: MyName  
geneIds: 1, 2, ..., 10 (total: 10)
geneIdType: Null
collectionType: Null  
setIdentifier: MyId
description:  
organism:  
pubMedIds:  
urls:  
contributor:  
setVersion: 0.0.1
creationDate:
> c(setName(myGset), setIdentifier(myGset)) ;
[1] "MyName" "MyId"
> # It was correctly created, now lets change just its name to OtherName
> setName(myGset) <- "OtherName";
> c(setName(myGset), setIdentifier(myGset))
[1] "OtherName"                                         
[2] "bdmgWorkstation2:28927:Tue Jan 24 12:09:13 2017:1"
> # As we can see, the setIdentifier has changed automatically
> details(myGset);                          
setName: OtherName  
geneIds: 1, 2, ..., 10 (total: 10)
geneIdType: Null
collectionType: Null  
setIdentifier: bdmgWorkstation2:28927:Tue Jan 24 12:09:13 2017:1
description:  
organism:  
pubMedIds:  
urls:  
contributor:  
setVersion: 0.0.1
creationDate:
> sessionInfo(); 
R Under development (unstable) (2017-01-04 r71888)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 13.04

locale:
[1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               
[3] LC_TIME=es_AR.UTF-8        LC_COLLATE=en_US.UTF-8     
[5] LC_MONETARY=es_AR.UTF-8    LC_MESSAGES=en_US.UTF-8    
[7] LC_PAPER=es_AR.UTF-8       LC_NAME=C                  
[9] LC_ADDRESS=C               LC_TELEPHONE=C             
[11] LC_MEASUREMENT=es_AR.UTF-8 LC_IDENTIFICATION=C        

attached base packages:
[1] stats4    parallel  stats     graphics  grDevices utils     datasets  
[8] methods   base

other attached packages:
[1] GSEABase_1.37.0      graph_1.53.0         annotate_1.53.1      
[4] XML_3.98-1.5         AnnotationDbi_1.37.1 IRanges_2.9.14       
[7] S4Vectors_0.13.7     Biobase_2.35.0       BiocGenerics_0.21.3  

loaded via a namespace (and not attached):
[1] Rcpp_0.12.9    digest_0.6.11  bitops_1.0-6   xtable_1.8-2   DBI_0.5-1      
[6] RSQLite_1.1-2  tools_3.4.0    RCurl_1.95-4.8 compiler_3.4.0 memoise_1.0.0

Not a bug but maybe a misguided feature. The idea is that the identifier is 'unique', so when you change the gene set, in any way, you get a new identifier. Otherwise, the information would be redundant with the set name.

Martin, thanks for you (really) fast reply.
I am getting confused with GeneSet-class slots:
setNames must be unique inside a GeneSetCollection, but setIdentifiers might not. As I am used to have the IDs to be unique then it is being hard to get used to it haha.
I get your idea about setIdentifiers, so I will have to use my workaroud:

> myGset <- GeneSet(as.character(1:10), setName="MyName", setIdentifier="MyId");
> old_setId <- setIdentifier(myGset);
> setName(myGset) <- "OtherName";
> setIdentifier(myGset) <- old_setId;

However, just to have it clear, how would you manually create the "GO:0000102" gene set? (I am just interested in ID and Name, no matter about genes, collection, etc).
Am I right as follows?

> fakeGenes <- as.character(1:10)
> myGOgset <- GeneSet(fakeGenes, setName="L-methionine secondary active transmembrane transporter activity", setIdentifier="GO:0000102");

thanks!!
Rodriguez, Juan Cruz.