processor/src/main/java/repacked/com/squareup/javawriter/JavaWriter.java
public String compressType(String type) {
    StringBuilder sb = new StringBuilder();
    if (this.packagePrefix == null) {
      throw new IllegalStateException();
    }

    Matcher m = TYPE_PATTERN.matcher(type);
    int pos = 0;
    while (true) {
      boolean found = m.find(pos);

      // Copy non-matching characters like "<".
      int typeStart = found ? m.start() : type.length();
      sb.append(type, pos, typeStart);

      if (!found) {
        break;
      }

      // Copy a single class name, shortening it if possible.
      String name = m.group(0);
      String imported = importedTypes.get(name);
      if (imported != null) {
        sb.append(imported);
      } else if (isClassInPackage(name, packagePrefix)) {
        String compressed = name.substring(packagePrefix.length());
        if (isAmbiguous(compressed)) {
          sb.append(name);
        } else {
          sb.append(compressed);
        }
      } else if (isClassInPackage(name, "java.lang.")) {
        sb.append(name.substring("java.lang.".length()));
      } else {
        sb.append(name);
      }
      pos = m.end();
    }
    return sb.toString();
  }
public String compressType(String type) {
    StringBuilder sb = new StringBuilder();
    if (this.packagePrefix == null) {
      throw new IllegalStateException();
    }

    Matcher m = TYPE_PATTERN.matcher(type);
    int pos = 0;
    while (true) {
      boolean found = m.find(pos);

      // Copy non-matching characters like "<".
      int typeStart = found ? m.start() : type.length();
      sb.append(type, pos, typeStart);

      if (!found) {
        break;
      }

      // Copy a single class name, shortening it if possible.
      String name = m.group(0);
      String imported = importedTypes.get(name);
      if (imported != null) {
        sb.append(imported);
      } else if (isClassInPackage(name, packagePrefix)) {
        String compressed = name.substring(packagePrefix.length());
        if (isAmbiguous(compressed)) {
          sb.append(name);
        } else {
          sb.append(compressed);
        }
      } else if (isClassInPackage(name, "java.lang.")) {
        sb.append(name.substring("java.lang.".length()));
      } else {
        sb.append(name);
      }
      pos = m.end();
    }
    return sb.toString();
  }
Try to compress a fully-qualified class name to only the class name.