* `tax: float = 10.5` has a default of `10.5`.
* `tags: List[str] = []` has a default of an empty list: `[]`.

but you might want to omit them from the result if they were not actually stored.

For example, if you have models with many optional attributes in a NoSQL database, but you don't want to send very long JSON responses full of default values.

* `expose_headers` - Indicate any response headers that should be made accessible to the browser. Defaults to `[]`.
* `max_age` - Sets a maximum time in seconds for browsers to cache CORS responses. Defaults to `600`.

  // +optional
  optional string host = 1;

  // IngressRuleValue represents a rule to route requests for this IngressRule.
  // If unspecified, the rule defaults to a http catch-all. Whether that sends
  // just traffic matching the host to the default backend or all traffic to the
  // default backend, is left to the controller fulfilling the Ingress. Http is
  // currently the only supported IngressRuleValue.
  // +optional

    This is the model specification for <code>${basedir}/profiles.xml</code>.
  ]]></description>
  <defaults>
    <default>
      <key>package</key>
      <value>org.apache.maven.profiles</value>
    </default>
  </defaults>
  <classes>
    <class rootElement="true" xml.tagName="profilesXml">
      <name>ProfilesRoot</name>
      <version>1.0.0</version>

  <name>Paramdoc</name>
  <description><![CDATA[Documentation on parameter expressions supported by Maven for use in plugins.]]></description>
  <defaults>
    <default>
      <key>package</key>
      <value>org.apache.maven.usability.plugin</value>
    </default>
  </defaults>
  <classes>
    <class rootElement="true" xml.tagName="paramdoc">
      <version>1.0.0</version>
      <name>ExpressionDocumentation</name>

    </mailingList>
  </mailingLists>

  <build>
    <plugins>
      <plugin>
        <groupId>inheritance.configuration</groupId>
        <artifactId>default</artifactId>
        <version>3.0</version>
        <configuration>
          <defaults><!-- equivalent to combine.children="merge" combine.self="merge" -->
            <!-- merge the content of the configuration element according to element name -->

import (
	"istio.io/istio/pkg/env"
	"istio.io/istio/pkg/log"
)

const (
	// Location to read istioctl defaults from
	defaultIstioctlConfig = "$HOME/.istioctl/config.yaml"
)

var (
	// IstioConfig is the name of the istioctl config file (if any)
	IstioConfig = env.Register("ISTIOCONFIG", defaultIstioctlConfig,
		"Default values for istioctl flags").Get()

	LoggingOptions = defaultLogOptions()

)

const (
	formatComment     = `'namespace' reflects current bucket/object list and 'access' reflects a journal of object operations, defaults to 'namespace'`
	queueDirComment   = `staging dir for undelivered messages e.g. '/home/events'`
	queueLimitComment = `maximum limit for undelivered messages, defaults to '100000'`
)

// Help template inputs for all notification targets
var (
	HelpWebhook = config.HelpKVS{
		config.HelpKV{

  <build>
    <plugins>
      <plugin>
        <groupId>inheritance.configuration</groupId>
        <artifactId>default</artifactId>
        <version>2.0</version>
        <configuration>
          <defaults>
            <parent-only>parent</parent-only>
            <parent>parent</parent>
          </defaults>
          <appends>
            <parent-only>parent</parent-only>
            <parent>parent</parent>

     * true}. If {@code false}, unknown elements will be ignored instead of causing a failure.
     */
    String IS_STRICT = "org.apache.maven.model.io.isStrict";

    /**
     * The key for the option to enable tracking of line/column numbers. This option is of type
     * {@link org.apache.maven.model.InputSource} and defaults to {@code null}. Providing an input source enables