A property may be _mutable_, meaning that it has both a `get()` method and `set()` method:

====
include::sample[dir="snippets/providers/property/kotlin",files="build.gradle.kts[tags=prop-managed]"]
include::sample[dir="snippets/providers/property/groovy",files="build.gradle[tags=prop-managed]"]
====

Or _read-only_, meaning that it has only a `get()` method.
The _read-only_ properties are _providers_:

====

   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method is similar to Java 8's {@code
   * Optional.orElseGet}, except when {@code supplier} returns {@code null}. In this case this
   * method throws an exception, whereas the Java 8+ method returns the {@code null} to the caller.
   *
   * @throws NullPointerException if this optional's value is absent and the supplier returns {@code

			"Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n" +
			"Keep-Alive: 300\r\n" +
			"Content-Length: 7\r\n" +
			"Proxy-Connection: keep-alive\r\n\r\n" +
			"abcdef\n???",

		&Request{
			Method: "GET",
			URL: &url.URL{
				Scheme: "http",
				Host:   "www.techcrunch.com",
				Path:   "/",
			},
			Proto:      "HTTP/1.1",
			ProtoMajor: 1,
			ProtoMinor: 1,
			Header: Header{

    private static final ImmutableMap<String, Method> typeVariableMethods;

    static {
      ImmutableMap.Builder<String, Method> builder = ImmutableMap.builder();
      for (Method method : TypeVariableImpl.class.getMethods()) {
        if (method.getDeclaringClass().equals(TypeVariableImpl.class)) {
          try {
            method.setAccessible(true);
          } catch (AccessControlException e) {

        expect:
        assertValidationFailsWith([
            error(methodShouldNotBeAnnotatedConfig { type('MyTask').kind('method').method('notAGetter').annotation('Input') }, 'validation_problems', 'ignored_annotations_on_method'),
            error(methodShouldNotBeAnnotatedConfig { type('MyTask.Options').kind('method').method('notANestedGetter').annotation('Input') }, 'validation_problems', 'ignored_annotations_on_method'),
        ])

        and:

}

// expandMethod substitutes type arguments in the i'th method for an
// instantiated receiver.
func (t *Named) expandMethod(i int) *Func {
	// t.orig.methods is not lazy. origm is the method instantiated with its
	// receiver type parameters (the "origin" method).
	origm := t.inst.orig.Method(i)
	assert(origm != nil)

	check := t.check
	// Ensure that the original method is type-checked.
	if check != nil {

  public void testAllOverloads_checkArgument() throws Exception {
    for (ImmutableList<Class<?>> sig : allSignatures(boolean.class)) {
      Method checkArgumentMethod =
          Preconditions.class.getMethod("checkArgument", sig.toArray(new Class<?>[] {}));
      checkArgumentMethod.invoke(null /* static method */, getParametersForSignature(true, sig));

      Object[] failingParams = getParametersForSignature(false, sig);

    assertThat(result).contains(address("2a03:2880:f029:11:face:b00c:0:2"))
    val request1 = server.takeRequest()
    assertThat(request1.method).isEqualTo("GET")
    val request2 = server.takeRequest()
    assertThat(request2.method).isEqualTo("GET")
    assertThat(listOf(request1.path, request2.path))
      .containsExactlyInAnyOrder(
        "/lookup?ct&dns=AAABAAABAAAAAAAABmdvb2dsZQNjb20AAAEAAQ",

    }

    public static <T> ModelType<T> returnType(Method method) {
        return new Simple<T>(method.getGenericReturnType());
    }

    public static <T> ModelType<T> declaringType(Method method) {
        return new Simple<T>(method.getDeclaringClass());
    }

    @Nullable
    public static <T> ModelType<T> paramType(Method method, int i) {
        Type[] parameterTypes = method.getGenericParameterTypes();

        failureDescriptionContains(missingValueMessage { property('input') })

        where:
        method << ["file", "files", "dir"]
    }

    def "optional null input files registered via TaskInputs.#method are allowed"() {
        buildFile << """
            task test {
                inputs.${method}({ null }) withPropertyName "input" optional(true)
                doLast {}
            }
        """