The important thing to keep in mind is that the `sub` key should have a unique identifier across the entire application, and it should be a string.

## Check it { #check-it }

/**
 * A specification of a {@link CacheBuilder} configuration.
 *
 * <p>{@code CacheBuilderSpec} supports parsing configuration off of a string, which makes it
 * especially useful for command-line configuration of a {@code CacheBuilder}.
 *
 * <p>The string syntax is a series of comma-separated keys or key-value pairs, each corresponding
 * to a {@code CacheBuilder} method.
 *
 * <ul>

/**
 * A specification of a {@link CacheBuilder} configuration.
 *
 * <p>{@code CacheBuilderSpec} supports parsing configuration off of a string, which makes it
 * especially useful for command-line configuration of a {@code CacheBuilder}.
 *
 * <p>The string syntax is a series of comma-separated keys or key-value pairs, each corresponding
 * to a {@code CacheBuilder} method.
 *
 * <ul>

  //    assigned prior to calling addListener, and addListener happens-before any invocation of the
  //    listener. Notably, this means that 'volatile' is unnecessary to make 'inputFuture' visible
  //    to the listener.
  //
  // 2. In done() where we may propagate cancellation to the input. In this case it is _not_ fine.

104A..104F    ; valid                  ;      ; NV8    # 3.0  MYANMAR SIGN LITTLE SECTION..MYANMAR SYMBOL GENITIVE
1050..1059    ; valid                                  # 3.0  MYANMAR LETTER SHA..MYANMAR VOWEL SIGN VOCALIC LL
105A..1099    ; valid                                  # 5.1  MYANMAR LETTER MON NGA..MYANMAR SHAN DIGIT NINE

to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software: you can redistribute it and/or modify

constraints.Min.message = {item} must be greater than or equal to {value}.
constraints.NotNull.message = {item} is required.
constraints.Null.message = {item} must be null.
constraints.Past.message = {item} must be a past value.
constraints.Pattern.message = {item} does not match "{regexp}".
constraints.Size.message = The size of {item} must be between {min} and {max}.

constraints.Min.message = {item} must be greater than or equal to {value}.
constraints.NotNull.message = {item} is required.
constraints.Null.message = {item} must be null.
constraints.Past.message = {item} must be a past value.
constraints.Pattern.message = {item} does not match "{regexp}".
constraints.Size.message = The size of {item} must be between {min} and {max}.

  /**
   * Constructs a new {@code CacheStats} instance.
   *
   * <p>Five parameters of the same type in a row is a bad thing, but this class is not constructed
   * by end users and is too fine-grained for a builder.
   */
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  public CacheStats(
      long hitCount,
      long missCount,
      long loadSuccessCount,

 *
 * @author Robert Konigsberg
 */
@GwtCompatible
@NullMarked
public class UnmodifiableCollectionTests {

  public static void assertMapEntryIsUnmodifiable(Entry<?, ?> entry) {
    try {
      // fine because the call is going to fail without modifying the entry
      @SuppressWarnings("unchecked")
      Entry<?, @Nullable Object> nullableValueEntry = (Entry<?, @Nullable Object>) entry;
      nullableValueEntry.setValue(null);