public java.lang.String getFilter() {
        java.lang.Object ref = filter_;
        if (!(ref instanceof java.lang.String)) {
          com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
          java.lang.String s = bs.toStringUtf8();
          filter_ = s;
          return s;
        } else {
          return (java.lang.String) ref;
        }
      }
<pre>
An optional list of query parameters specified as JSON text in the
form of:

`{"agentPoolNames":["agentpool1","agentpool2",...]}`

Since `agentPoolNames` support multiple values, its values must be
specified with array notation. When the filter is either empty or not
provided, the list returns all agent pools for the project.
</pre>

<code>string filter = 2;</code>

@return The filter.
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferProto.java