SystemEnvironmentProvider.java
package com.google.auth.oauth2;
import java.io.Serializable;
/** Represents the default system environment provider. */
class SystemEnvironmentProvider implements EnvironmentProvider, Serializable {
  static final SystemEnvironmentProvider INSTANCE = new SystemEnvironmentProvider();
  private static final long serialVersionUID = -4698164985883575244L;
  private SystemEnvironmentProvider() {}
  @Override
  public String getEnv(String name) {
    return System.getenv(name);
  }
  public static SystemEnvironmentProvider getInstance() {
    return INSTANCE;
  }
}