##annotation
* The concept : description of the program. To the computer to read. It can be declared in front of the packages, classes, fields, methods, local variables, parameters and the like of the method for these elements will be described. (Note: with a text description of the program to the programmer)
* Role Category :
① write the document: Notes identified by code generation document generation API documentation [for example]
② code analysis: analysis of the code by annotating code using reflection [ID]
③ compilation checking: by annotating code identified so that the compiler can compile basic checks, etc.] [@Override