@java.lang.Override
  public int hashCode() {
    if (memoizedHashCode != 0) {
      return memoizedHashCode;
    }
    int hash = 41;
    hash = (19 * hash) + getDescriptor().hashCode();
    hash = (37 * hash) + PARENT_FIELD_NUMBER;
    hash = (53 * hash) + getParent().hashCode();
    hash = (37 * hash) + PAGE_SIZE_FIELD_NUMBER;
    hash = (53 * hash) + getPageSize();
    hash = (37 * hash) + PAGE_TOKEN_FIELD_NUMBER;
    hash = (53 * hash) + getPageToken().hashCode();
    hash = (37 * hash) + FILTER_FIELD_NUMBER;
    hash = (53 * hash) + getFilter().hashCode();
    hash = (29 * hash) + getUnknownFields().hashCode();
    memoizedHashCode = hash;
    return hash;
  }
<pre>
Optional. Filter specifying constraints of a list operation.
Specify the constraint by the format of "key=value", where key must be
"src" or "tgt", and the value must be a valid language code.
For multiple restrictions, concatenate them by "AND" (uppercase only),
such as: "src=en-US AND tgt=zh-CN". Notice that the exact match is used
here, which means using 'en-US' and 'en' can lead to different results,
which depends on the language code you used when you create the glossary.
For the unidirectional glossaries, the "src" and "tgt" add restrictions
on the source and target language code separately.
For the equivalent term set glossaries, the "src" and/or "tgt" add
restrictions on the term set.
For example: "src=en-US AND tgt=zh-CN" will only pick the unidirectional
glossaries which exactly match the source language code as "en-US" and the
target language code "zh-CN", but all equivalent term set glossaries which
contain "en-US" and "zh-CN" in their language set will be picked.
If missing, no filtering is performed.
</pre>

<code>string filter = 4 [(.google.api.field_behavior) = OPTIONAL];</code>

@return The bytes for filter.
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/ListGlossariesRequest.java