Add schema provided checks for library.properties includes field

Author: per1234

check/checkconfigurations/checkconfigurations.go

@@ -161,6 +161,21 @@ var configurations = []Type{
 		ErrorModes:      nil,
 		CheckFunction:   checkfunctions.LibraryPropertiesDependsFieldNotInIndex,
 	},
+	{
+		ProjectType:     projecttype.Library,
+		Category:        "library.properties",
+		Subcategory:     "includes field",
+		ID:              "",
+		Brief:           "includes blank",
+		Description:     `Caused the "Sketch > Include library" feature of previous IDE versions to add an empty #include directive to the sketch.`,
+		MessageTemplate: "Empty library.properties includes field. Please either define includes or remove this optional field. See https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format",
+		DisableModes:    nil,
+		EnableModes:     []checkmode.Type{checkmode.All},
+		InfoModes:       nil,
+		WarningModes:    []checkmode.Type{checkmode.Permissive},
+		ErrorModes:      []checkmode.Type{checkmode.Default},
+		CheckFunction:   checkfunctions.LibraryPropertiesIncludesFieldLTMinLength,
+	},
 	{
 		ProjectType:     projecttype.Sketch,
 		Category:        "structure",

check/checkfunctions/library.go

@@ -140,6 +140,23 @@ func LibraryPropertiesDependsFieldNotInIndex() (result checkresult.Type, output
 	return checkresult.Pass, ""
 }
 
+// LibraryPropertiesNameFieldLTMinLength checks if the library.properties "includes" value is less than the minimum length.
+func LibraryPropertiesIncludesFieldLTMinLength() (result checkresult.Type, output string) {
+	if checkdata.LibraryPropertiesLoadError() != nil {
+		return checkresult.NotRun, ""
+	}
+
+	if !checkdata.LibraryProperties().ContainsKey("includes") {
+		return checkresult.NotRun, ""
+	}
+
+	if schema.PropertyLessThanMinLength("includes", checkdata.LibraryPropertiesSchemaValidationResult()[compliancelevel.Specification], configuration.SchemasPath()) {
+		return checkresult.Fail, ""
+	}
+
+	return checkresult.Pass, ""
+}
+
 // nameInLibraryManagerIndex returns whether there is a library in Library Manager index using the given name.
 func nameInLibraryManagerIndex(name string) bool {
 	libraries := checkdata.LibraryManagerIndex()["libraries"].([]interface{})