@java.lang.Override
  public boolean hasSystemInstruction() {
    return ((bitField0_ & 0x00000001) != 0);
  }
<pre>
Optional. Input only. Immutable. Developer set system instruction.
Currently, text only
</pre>

<code>
.google.cloud.vertexai.v1.Content system_instruction = 3 [(.google.api.field_behavior) = OPTIONAL, (.google.api.field_behavior) = IMMUTABLE, (.google.api.field_behavior) = INPUT_ONLY];
</code>

@return Whether the systemInstruction field is set.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/CachedContent.java