logback-android/src/main/java/ch/qos/logback/core/pattern/util/AlmostAsIsEscapeUtil.java
public void escape(String escapeChars, StringBuffer buf, char next,
      int pointer) {
    super.escape(""+CoreConstants.PERCENT_CHAR+CoreConstants.RIGHT_PARENTHESIS_CHAR, buf, next, pointer);
  }
public void escape(String escapeChars, StringBuffer buf, char next,
      int pointer) {
    super.escape(""+CoreConstants.PERCENT_CHAR+CoreConstants.RIGHT_PARENTHESIS_CHAR, buf, next, pointer);
  }
Do not perform any character escaping, except for '%', and ')'.

<p>
Here is the rationale. First, filename patterns do not include escape
combinations such as \r or \n. Moreover, characters which have special
meaning in logback parsers, such as '{', or '}' cannot be part of file
names (so me thinks). The left parenthesis character has special meaning
only if it is preceded by %. Thus, the only characters that needs escaping
are '%' and ')'.

<p>
Note that this method assumes that it is called after the escape character
has been consumed.