public java.lang.String getExternalId() {
      java.lang.Object ref = externalId_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        externalId_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
Required. Client side company identifier, used to uniquely identify the
company.

The maximum number of allowed characters is 255.
</pre>

<code>string external_id = 3 [(.google.api.field_behavior) = REQUIRED];</code>

@return The externalId.
java-talent/proto-google-cloud-talent-v4/src/main/java/com/google/cloud/talent/v4/Company.java