@SuppressWarnings("unchecked") // Assume all default values are generics safe.
    T defaultValue = (T) defaultValues.getInstance(rawType);
    if (defaultValue != null) {
      return defaultValue;
    }
    @SuppressWarnings("unchecked") // ArbitraryInstances always returns generics-safe dummies.
    T value = (T) ArbitraryInstances.get(rawType);
    if (value != null) {
      return value;
    }

    @SuppressWarnings("unchecked") // Assume all default values are generics safe.
    T defaultValue = (T) defaultValues.getInstance(rawType);
    if (defaultValue != null) {
      return defaultValue;
    }
    @SuppressWarnings("unchecked") // ArbitraryInstances always returns generics-safe dummies.
    T value = (T) ArbitraryInstances.get(rawType);
    if (value != null) {
      return value;
    }

        return new SystemPropertyRead() {
            @Override
            String getGroovyExpression() {
                return "Integer.getInteger(\"$name\", $defaultValue)"
            }

            @Override
            String getKotlinExpression() {
                return "Integer.getInteger(\"$name\", $defaultValue)"
            }
        }
    }

          <description></description>
          <type>boolean</type>
          <defaultValue>false</defaultValue>
        </field>
        <field>
          <name>inheritedByDefault</name>
          <version>1.0.0+</version>
          <description></description>
          <type>boolean</type>
          <defaultValue>true</defaultValue>
        </field>
        <field>
          <name>requiredJavaVersion</name>

            }
        }
    }

    static EnvVariableRead getEnvGetOrDefault(String name, String defaultValue) {
        return new EnvVariableRead() {
            @Override
            String getKotlinExpression() {
                return "System.getenv().getOrDefault(\"$name\", \"$defaultValue\")"
            }
        }
    }

    static EnvVariableRead getEnvContainsKey(String name) {

}


private
fun InternalOptions.getInternalFlag(systemPropertyName: String, defaultValue: Boolean = false): Boolean =
    getOption(InternalFlag(systemPropertyName, defaultValue)).get()


private
fun InternalOptions.getInternalString(systemPropertyName: String, defaultValue: String?) =

                isolatedProjects = Option.Value.value(false)
            }))
        )
        assertThat(
            cacheKeyStringFromStartParameter {
                isolatedProjects = Option.Value.defaultValue(false)
            },
            equalTo(cacheKeyStringFromStartParameter { })
        )
        assertThat(
            cacheKeyStringFromStartParameter {

    // We assume that all defaults are generics-safe, even if they aren't,
    // we take the risk.
    @SuppressWarnings("unchecked")
    T defaultValue = (T) defaults.getInstance(type.getRawType());
    if (defaultValue != null) {
      return defaultValue;
    }
    @SuppressWarnings("unchecked") // All arbitrary instances are generics-safe
    T arbitrary = (T) ArbitraryInstances.get(type.getRawType());

}

func registerEnvironment[T env.Parseable](name string, defaultValue T, usage string) {
	envName := strings.Replace(strings.ToUpper(name), "-", "_", -1)
	// Note: we do not rely on istio env package to retrieve configuration. We relies on viper.
	// This is just to make sure the reference doc tool can generate doc with these vars as env variable at istio.io.
	env.Register(envName, defaultValue, usage)
	bindViper(name)
}

    // We assume that all defaults are generics-safe, even if they aren't,
    // we take the risk.
    @SuppressWarnings("unchecked")
    T defaultValue = (T) defaults.getInstance(type.getRawType());
    if (defaultValue != null) {
      return defaultValue;
    }
    @SuppressWarnings("unchecked") // All arbitrary instances are generics-safe
    T arbitrary = (T) ArbitraryInstances.get(type.getRawType());