wire up UserAgentFactory and add e2e test

pkg/ottl/e2e/e2e_test.go

@@ -736,6 +736,15 @@ func Test_e2e_converters(t *testing.T) {
 				m.PutStr("bar", "pass")
 			},
 		},
+		{
+			statement: `set(attributes["test"], UserAgent("curl/7.81.0"))`,
+			want: func(tCtx ottllog.TransformContext) {
+				m := tCtx.GetLogRecord().Attributes().PutEmptyMap("test")
+				m.PutStr("user_agent.original", "curl/7.81.0")
+				m.PutStr("user_agent.name", "curl")
+				m.PutStr("user_agent.version", "7.81.0")
+			},
+		},
 	}
 
 	for _, tt := range tests {

pkg/ottl/ottlfuncs/func_useragent.go

@@ -4,12 +4,30 @@
 package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
 import (
 	"context"
+	"fmt"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
 	"github.com/ua-parser/uap-go/uaparser"
 	semconv "go.opentelemetry.io/collector/semconv/v1.25.0"
 )
 
+type UserAgentArguments[K any] struct {
+	UserAgent ottl.StringGetter[K]
+}
+
+func NewUserAgentFactory[K any]() ottl.Factory[K] {
+	return ottl.NewFactory("UserAgent", &UserAgentArguments[K]{}, createUserAgentFunction[K])
+}
+
+func createUserAgentFunction[K any](_ ottl.FunctionContext, oArgs ottl.Arguments) (ottl.ExprFunc[K], error) {
+	args, ok := oArgs.(*UserAgentArguments[K])
+	if !ok {
+		return nil, fmt.Errorf("URLFactory args must be of type *URLArguments[K]")
+	}
+
+	return userAgent[K](args.UserAgent), nil
+}
+
 func userAgent[K any](userAgentSource ottl.StringGetter[K]) ottl.ExprFunc[K] { //revive:disable-line:var-naming
 	return func(ctx context.Context, tCtx K) (any, error) {
 		userAgentString, err := userAgentSource.Get(ctx, tCtx)

pkg/ottl/ottlfuncs/functions.go

@@ -84,6 +84,7 @@ func converters[K any]() []ottl.Factory[K] {
 		NewUnixSecondsFactory[K](),
 		NewUUIDFactory[K](),
 		NewURLFactory[K](),
+		NewUserAgentFactory[K](),
 		NewAppendFactory[K](),
 		NewYearFactory[K](),
 		NewHexFactory[K](),