package com.google.sps.agents;
 
// Imports the Google Cloud client library
import com.google.cloud.dialogflow.v2.QueryInput;
import com.google.cloud.dialogflow.v2.QueryResult;
import com.google.cloud.translate.*;
import com.google.protobuf.Struct;
import com.google.protobuf.Value;
import com.google.sps.data.Output;
import com.google.sps.agents.Agent;
import com.google.sps.utils.AgentUtils;
import java.io.IOException;
import java.util.Map;
 
/**
 * Translate Agent
 */
public class TranslateAgent implements Agent {
    private final String intentName;
    private String text;
    private String languageTo;
    private String languageFrom;
    private String languageToCode;
    private String languageFromCode;
    private String translatedString;
    private String fulfillment;
 
    public TranslateAgent(String intentName, Map<String, Value> parameters) {
        this.intentName = intentName;
        setParameters(parameters);
    }

	@Override 
	public void setParameters(Map<String, Value> parameters) {
        System.out.println(parameters);
        text = parameters.get("text").getStringValue();
        languageTo = parameters.get("lang-to").getStringValue();
        languageFrom = parameters.get("lang-from").getStringValue();
        languageToCode = AgentUtils.getLanguageCode(languageTo);
        languageFromCode = AgentUtils.getLanguageCode(languageFrom);
        Translation translation = translate(text, languageFromCode, languageToCode);
        translatedString = translation.getTranslatedText();

        if (languageToCode == null || languageFromCode == null) {
            fulfillment = null;
        } else {
            fulfillment = text + " in " + languageTo + " is: " + translatedString;
        }
	}
	
	@Override
	public String getOutput() {
        return fulfillment;
	}

	@Override
	public String getDisplay() {
		return null;
	}

	@Override
	public String getRedirect() {
		return null;
    }

    public static Translation translate(String text, String languageFromCode, String languageToCode) {
        Translate translate = TranslateOptions.getDefaultInstance().getService();

        Translation translation =
        translate.translate(
            text,
            Translate.TranslateOption.sourceLanguage(languageFromCode),
            Translate.TranslateOption.targetLanguage(languageToCode),
            // Use "base" for standard edition, "nmt" for the premium model.
            Translate.TranslateOption.model("nmt"));

        System.out.printf("TranslatedText:\nText: %s\n", translation.getTranslatedText());
        return translation;
    }



}

package com.google.sps.agents;
 
// Imports the Google Cloud client library
import com.google.cloud.dialogflow.v2.QueryInput;
import com.google.cloud.dialogflow.v2.QueryResult;
import com.google.cloud.translate.*;
import com.google.protobuf.Struct;
import com.google.protobuf.Value;
import com.google.sps.data.Output;
import com.google.sps.agents.Agent;
import com.google.sps.utils.AgentUtils;
import java.io.IOException;
import java.util.Map;
 
/**
 * Translate Agent
 */
public class TranslateAgent implements Agent {
  private final String intentName;
  private String text;
  private String languageTo;
  private String languageFrom;
  private String languageToCode;
  private String languageFromCode;
  private String translatedString;
  private String fulfillment = null;
  private String display = null
  private String redirect = null;

  public TranslateAgent(String intentName, Map<String, Value> parameters) {
    this.intentName = intentName;
    setParameters(parameters);
  }

  @Override 
  public void setParameters(Map<String, Value> parameters) {
    System.out.println(parameters);
    text = parameters.get("text").getStringValue();
    languageTo = parameters.get("lang-to").getStringValue();
    languageFrom = parameters.get("lang-from").getStringValue();
    languageToCode = AgentUtils.getLanguageCode(languageTo);
    languageFromCode = AgentUtils.getLanguageCode(languageFrom);
    Translation translation = translate(text, languageFromCode, languageToCode);
    translatedString = translation.getTranslatedText();

    if (languageToCode == null || languageFromCode == null) {
      fulfillment = null;
    } else {
      fulfillment = text + " in " + languageTo + " is: " + translatedString;
    }
  }

  @Override
  public String getOutput() {
    return fulfillment;
  }

  @Override
  public String getDisplay() {
    return display;
  }

  @Override
  public String getRedirect() {
    return redirect;
  }

  public static Translation translate(String text, String languageFromCode, String languageToCode) {
    Translate translate = TranslateOptions.getDefaultInstance().getService();

    Translation translation =
    translate.translate(
      text,
      Translate.TranslateOption.sourceLanguage(languageFromCode),
      Translate.TranslateOption.targetLanguage(languageToCode),
      // Use "base" for standard edition, "nmt" for the premium model.
      Translate.TranslateOption.model("nmt"));

    System.out.printf("TranslatedText:\nText: %s\n", translation.getTranslatedText());
    return translation;
  }
}

Update TranslateAgent.java