apollo-common/src/main/java/com/ctrip/framework/apollo/common/config/RefreshableConfig.java/RefreshableConfig/getBooleanProperty
class RefreshableConfig:  public boolean getBooleanProperty(String key, boolean defaultValue) {
    try {
      String value = getValue(key);
      return value == null ? defaultValue : "true".equals(value);
    } catch (Throwable e) {
      Tracer.logError("Get boolean property failed.", e);
      return defaultValue;
    }
  }