integrate request builder into HTTP client for googleapis support (#157)

builder/body_option.go

@@ -0,0 +1,22 @@
+package builder
+
+const (
+	singleWildcard string = "*"
+	doubleWildcard string = "**"
+)
+
+type bodyOption string
+
+func (o bodyOption) String() string { return string(o) }
+
+func (o bodyOption) isFullBody() bool {
+	return o.String() == singleWildcard
+}
+
+func (o bodyOption) isWithoutBody() bool {
+	return o == ""
+}
+
+func (o bodyOption) isSingleField() bool {
+	return o != "" && o.String() != singleWildcard
+}