Fix `go vet` issues

Test: go vet ./...
Change-Id: Ifb936ccc5e2b5a2c3fcbbbcb54f680e2973ea1b3
diff --git a/android/config_test.go b/android/config_test.go
index 72942eb..274d59f 100644
--- a/android/config_test.go
+++ b/android/config_test.go
@@ -50,7 +50,7 @@
 }
 
 type configType struct {
-	populateMe *bool `json:"omitempty"`
+	PopulateMe *bool `json:"omitempty"`
 }
 
 func (c *configType) SetDefaultConfig() {
@@ -60,7 +60,7 @@
 func TestValidateConfigAnnotations(t *testing.T) {
 	config := configType{}
 	err := validateConfigAnnotations(&config)
-	expectedError := `Field configType.populateMe has tag json:"omitempty" which specifies to change its json field name to "omitempty".
+	expectedError := `Field configType.PopulateMe has tag json:"omitempty" which specifies to change its json field name to "omitempty".
 Did you mean to use an annotation of ",omitempty"?
 (Alternatively, to change the json name of the field, rename the field in source instead.)`
 	if err.Error() != expectedError {