logback-android/src/main/java/ch/qos/logback/core/util/OptionHelper.java
public static String getEnv(String key) {
    try {
      return System.getenv(key);
    } catch (SecurityException e) {
      return null;
    }
  }
public static String getEnv(String key) {
    try {
      return System.getenv(key);
    } catch (SecurityException e) {
      return null;
    }
  }
Lookup a key from the environment.

@param key the environment variable's key
@return value corresponding to key from the OS environment