logback-android/src/main/java/ch/qos/logback/core/util/OptionHelper.java
public static boolean toBoolean(String value, boolean defaultValue) {
    if (value == null) {
      return defaultValue;
    }

    String trimmedVal = value.trim();

    if ("true".equalsIgnoreCase(trimmedVal)) {
      return true;
    }

    if ("false".equalsIgnoreCase(trimmedVal)) {
      return false;
    }

    return defaultValue;
  }
public static boolean toBoolean(String value, boolean defaultValue) {
    if (value == null) {
      return defaultValue;
    }

    String trimmedVal = value.trim();

    if ("true".equalsIgnoreCase(trimmedVal)) {
      return true;
    }

    if ("false".equalsIgnoreCase(trimmedVal)) {
      return false;
    }

    return defaultValue;
  }
If <code>value</code> is "true", then <code>true</code> is returned. If
<code>value</code> is "false", then <code>true</code> is returned.
Otherwise, <code>default</code> is returned.
<p>
Case of value is unimportant.
@param value string to be evaluated
@param defaultValue default value if value could not be converted
@return the equivalent boolean value