Infinite recursion with custom type mapping

[vearutop]

If type mapped structure is nested in another structure, infinite recursion happens with

runtime: goroutine stack exceeds 1000000000-byte limit
fatal error: stack overflow

runtime stack:
runtime.throw(0x137c04d, 0xe)
        /usr/local/Cellar/go/1.9/libexec/src/runtime/panic.go:605 +0x95
runtime.newstack(0x0)
        /usr/local/Cellar/go/1.9/libexec/src/runtime/stack.go:1050 +0x73b
runtime.morestack()
        /usr/local/Cellar/go/1.9/libexec/src/runtime/asm_amd64.s:415 +0x86

goroutine 9 [running]:
github.com/lazada/swgen.(*Generator).ParseDefinition(0xc4601ff000, 0x1308de0, 0x13b74a0, 0xc4200a6ce8, 0x1, 0x0, 0x0, 0x0, 0x0, 0x1379c89, ...)
        /Users/vpoturaev/golang/src/github.com/lazada/swgen/parser.go:108 +0x1d13 fp=0xc440201338 sp=0xc440201330 pc=0x12b88b3
github.com/lazada/swgen.(*Generator).ParseDefinition(0xc4601ff000, 0x1334780, 0xc4200e88c0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
        /Users/vpoturaev/golang/src/github.com/lazada/swgen/parser.go:138 +0x1c45 fp=0xc440202c38 sp=0xc440201338 pc=0x12b87e5
github.com/lazada/swgen.(*Generator).parseDefInQueue(0xc4601ff000)
        /Users/vpoturaev/golang/src/github.com/lazada/swgen/parser.go:350 +0xf8 fp=0xc440202d78 sp=0xc440202c38 pc=0x12ba358
github.com/lazada/swgen.(*Generator).ParseDefinition(0xc4601ff000, 0x131f060, 0xc42007d320, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1379c89, ...)
        /Users/vpoturaev/golang/src/github.com/lazada/swgen/parser.go:206 +0xd02 fp=0xc440204678 sp=0xc440202d78 pc=0x12b78a2
github.com/lazada/swgen.(*Generator).ParseDefinition(0xc4601ff000, 0x1350700, 0xc42001be30, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
        /Users/vpoturaev/golang/src/github.com/lazada/swgen/parser.go:138 +0x1c45 fp=0xc440205f78 sp=0xc440204678 pc=0x12b87e5

Sample:

type typeMapHolder struct {
	M typeMap `json:"m"`
}

type typeMap struct {
	R1 int `json:"1"`
	R2 int `json:"2"`
	R3 int `json:"3"`
	R4 int `json:"4"`
	R5 int `json:"5"`
}

gen.AddTypeMap(typeMap{}, map[string]int{})