1. A method for annotation, comprising: running an initial build file; generating, based on one or more annotations predefined in a folder, an index file as the initial build the is run, wherein the index file includes first and second strings, wherein the first string defines a key specifying one of the one or more predefined annotations, wherein the second string defines a value specifying a name of a class that is mapped to the annotation, wherein the folder is added as an indexed annotation; archiving the index file with the one or more predefined mapped annotations and class; and looking up, based on a given annotation, the index file to seek one or more classes associated with the given annotation.