feat(rc):Add exposurePercent to ExperimentValues (#1201)

* Add exposurePercent to ExperimentValues

* fix comments

* fix build

* Apply suggestions from code review

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* fix build

* fix build

* fix build

* fix build

* fix build

* fix build

* fix build

* resolved comments

* resolved comments

* resolved comments

* resolved comments

* Update TemplateResponse.java

* Update Template.java

---------

Co-authored-by: Varun Rathore <varunrathore@google.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: 3 people

src/main/java/com/google/firebase/remoteconfig/ParameterValue.java

@@ -26,14 +26,12 @@
 import com.google.firebase.remoteconfig.internal.TemplateResponse.ParameterValueResponse;
 import com.google.firebase.remoteconfig.internal.TemplateResponse.PersonalizationValueResponse;
 import com.google.firebase.remoteconfig.internal.TemplateResponse.RolloutValueResponse;
-
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 
-/**
- * Represents a Remote Config parameter value that can be used in a {@link Template}.
- */
+/** Represents a Remote Config parameter value 
+ * that can be used in a 
+ * {@link Template}. */
 public abstract class ParameterValue {
 
   /**
@@ -82,17 +80,18 @@ public static PersonalizationValue ofPersonalization(String personalizationId) {
    *
    * @param experimentId The experiment ID.
    * @param variantValues The list of experiment variant values.
+   * @param exposurePercent The exposure percentage of the experiment.
    * @return A {@link ParameterValue.ExperimentValue} instance.
    */
-  public static ExperimentValue ofExperiment(String experimentId,
-                                   List<ExperimentVariantValue> variantValues) {
-    return new ExperimentValue(experimentId, variantValues);
+  public static ExperimentValue ofExperiment(
+      String experimentId, List<ExperimentVariantValue> variantValues, double exposurePercent) {
+    return new ExperimentValue(experimentId, variantValues, exposurePercent);
   }
 
   abstract ParameterValueResponse toParameterValueResponse();
 
   static ParameterValue fromParameterValueResponse(
-          @NonNull ParameterValueResponse parameterValueResponse) {
+      @NonNull ParameterValueResponse parameterValueResponse) {
     checkNotNull(parameterValueResponse);
     if (parameterValueResponse.isUseInAppDefault()) {
       return ParameterValue.inAppDefault();
@@ -102,7 +101,7 @@ static ParameterValue fromParameterValueResponse(
       // Protobuf serialization does not set values for fields on the wire when
       // they are equal to the default value for the field type. When deserializing,
       // can appear as the value not being set. Explicitly handle default value for
-      // the percent field since 0 is a valid value. 
+      // the percent field since 0 is a valid value.
       double percent = 0;
       if (rv.getPercent() != null) {
         percent = rv.getPercent();
@@ -115,18 +114,26 @@ static ParameterValue fromParameterValueResponse(
     }
     if (parameterValueResponse.getExperimentValue() != null) {
       ExperimentValueResponse ev = parameterValueResponse.getExperimentValue();
-      List<ExperimentVariantValue> variantValues = ev.getExperimentVariantValues().stream()
-          .map(evv -> new ExperimentVariantValue(
-            evv.getVariantId(),  evv.getValue(), evv.getNoChange()))
-          .collect(toList());
-      return ParameterValue.ofExperiment(ev.getExperimentId(), variantValues);
+      List<ExperimentVariantValue> variantValues =
+          ev.getExperimentVariantValues().stream()
+              .map(
+                  evv ->
+                      new ExperimentVariantValue(
+                          evv.getVariantId(), evv.getValue(), evv.getNoChange()))
+              .collect(toList());
+      // Handle null exposurePercent by defaulting to 0
+      double exposurePercent = 0;
+      if (ev.getExposurePercent() != null) {
+        exposurePercent = ev.getExposurePercent();
+      }
+      return ParameterValue.ofExperiment(
+          ev.getExperimentId(), variantValues, exposurePercent);
     }
     return ParameterValue.of(parameterValueResponse.getValue());
   }
 
   /**
-   * Represents an explicit Remote Config parameter value with a value that the
-   * parameter is set to.
+   * Represents an explicit Remote Config parameter value with a value that the parameter is set to.
    */
   public static final class Explicit extends ParameterValue {
 
@@ -147,8 +154,7 @@ public String getValue() {
 
     @Override
     ParameterValueResponse toParameterValueResponse() {
-      return new ParameterValueResponse()
-              .setValue(this.value);
+      return new ParameterValueResponse().setValue(this.value);
     }
 
     @Override
@@ -169,9 +175,7 @@ public int hashCode() {
     }
   }
 
-  /**
-   * Represents an in app default parameter value.
-   */
+  /** Represents an in app default parameter value. */
   public static final class InAppDefault extends ParameterValue {
 
     @Override
@@ -191,9 +195,7 @@ public boolean equals(Object o) {
     }
   }
 
-  /**
-   * Represents a Rollout value.
-   */
+  /** Represents a Rollout value. */
   public static final class RolloutValue extends ParameterValue {
     private final String rolloutId;
     private final String value;
@@ -224,8 +226,8 @@ public String getValue() {
     }
 
     /**
-     * Gets the rollout percentage representing the exposure of rollout value
-     * in the target audience.
+     * Gets the rollout percentage representing the exposure of rollout value in the target
+     * audience.
      *
      * @return Percentage of audience exposed to the rollout
      */
@@ -235,11 +237,12 @@ public double getPercent() {
 
     @Override
     ParameterValueResponse toParameterValueResponse() {
-      return new ParameterValueResponse().setRolloutValue(
+      return new ParameterValueResponse()
+          .setRolloutValue(
               new RolloutValueResponse()
-                      .setRolloutId(this.rolloutId)
-                      .setValue(this.value)
-                      .setPercent(this.percent));
+                  .setRolloutId(this.rolloutId)
+                  .setValue(this.value)
+                  .setPercent(this.percent));
     }
 
     @Override
@@ -252,8 +255,8 @@ public boolean equals(Object o) {
       }
       RolloutValue that = (RolloutValue) o;
       return Double.compare(that.percent, percent) == 0
-              && Objects.equals(rolloutId, that.rolloutId)
-              && Objects.equals(value, that.value);
+          && Objects.equals(rolloutId, that.rolloutId)
+          && Objects.equals(value, that.value);
     }
 
     @Override
@@ -262,9 +265,7 @@ public int hashCode() {
     }
   }
 
-  /**
-   * Represents a Personalization value.
-   */
+  /** Represents a Personalization value. */
   public static final class PersonalizationValue extends ParameterValue {
     private final String personalizationId;
 
@@ -283,9 +284,9 @@ public String getPersonalizationId() {
 
     @Override
     ParameterValueResponse toParameterValueResponse() {
-      return new ParameterValueResponse().setPersonalizationValue(
-              new PersonalizationValueResponse()
-                      .setPersonalizationId(this.personalizationId));
+      return new ParameterValueResponse()
+          .setPersonalizationValue(
+              new PersonalizationValueResponse().setPersonalizationId(this.personalizationId));
     }
 
     @Override
@@ -306,9 +307,7 @@ public int hashCode() {
     }
   }
 
-  /**
-   * Represents a specific variant within an Experiment.
-   */
+  /** Represents a specific variant within an Experiment. */
   public static final class ExperimentVariantValue {
     private final String variantId;
     private final String value;
@@ -384,8 +383,8 @@ public boolean equals(Object o) {
       }
       ExperimentVariantValue that = (ExperimentVariantValue) o;
       return noChange == that.noChange
-              && Objects.equals(variantId, that.variantId)
-              && Objects.equals(value, that.value);
+          && Objects.equals(variantId, that.variantId)
+          && Objects.equals(value, that.value);
     }
 
     @Override
@@ -394,16 +393,17 @@ public int hashCode() {
     }
   }
 
-  /**
-   * Represents an Experiment value.
-   */
+  /** Represents an Experiment value. */
   public static final class ExperimentValue extends ParameterValue {
     private final String experimentId;
     private final List<ExperimentVariantValue> variantValues;
+    private final double exposurePercent;
 
-    private ExperimentValue(String experimentId, List<ExperimentVariantValue> variantValues) {
+    private ExperimentValue(
+        String experimentId, List<ExperimentVariantValue> variantValues, double exposurePercent) {
       this.experimentId = experimentId;
       this.variantValues = variantValues;
+      this.exposurePercent = exposurePercent;
     }
 
     /**
@@ -415,6 +415,15 @@ public String getExperimentId() {
       return experimentId;
     }
 
+    /**
+     * Gets the exposure percentage of the experiment linked to this value.
+     *
+     * @return Exposure percentage of the experiment linked to this value.
+     */
+    public double getExposurePercent() {
+      return exposurePercent;
+    }
+
     /**
      * Gets a collection of variant values served by the experiment.
      *
@@ -426,16 +435,21 @@ public List<ExperimentVariantValue> getExperimentVariantValues() {
 
     @Override
     ParameterValueResponse toParameterValueResponse() {
-      List<ExperimentVariantValueResponse> variantValueResponses = variantValues.stream()
-          .map(variantValue -> new ExperimentVariantValueResponse()
-              .setVariantId(variantValue.getVariantId())
-              .setValue(variantValue.getValue())
-              .setNoChange(variantValue.getNoChange()))
-          .collect(toList());
-      return new ParameterValueResponse().setExperimentValue(
+      List<ExperimentVariantValueResponse> variantValueResponses =
+          variantValues.stream()
+              .map(
+                  variantValue ->
+                      new ExperimentVariantValueResponse()
+                          .setVariantId(variantValue.getVariantId())
+                          .setValue(variantValue.getValue())
+                          .setNoChange(variantValue.getNoChange()))
+              .collect(toList());
+      return new ParameterValueResponse()
+          .setExperimentValue(
               new ExperimentValueResponse()
-                      .setExperimentId(this.experimentId)
-                      .setExperimentVariantValues(variantValueResponses));
+                  .setExperimentId(this.experimentId)
+                  .setExperimentVariantValues(variantValueResponses)
+                  .setExposurePercent(this.exposurePercent));
     }
 
     @Override
@@ -448,12 +462,13 @@ public boolean equals(Object o) {
       }
       ExperimentValue that = (ExperimentValue) o;
       return Objects.equals(experimentId, that.experimentId)
-              && Objects.equals(variantValues, that.variantValues);
+          && Objects.equals(variantValues, that.variantValues)
+          && Double.compare(that.exposurePercent, exposurePercent) == 0;
     }
 
     @Override
     public int hashCode() {
-      return Objects.hash(experimentId, variantValues);
+      return Objects.hash(experimentId, variantValues, exposurePercent);
     }
   }
 }

src/main/java/com/google/firebase/remoteconfig/Template.java

@@ -60,7 +60,7 @@ public Template(String etag) {
     this((String) null);
   }
 
-  Template(@NonNull TemplateResponse templateResponse) {
+  Template(@NonNull TemplateResponse templateResponse) throws FirebaseRemoteConfigException {
     checkNotNull(templateResponse);
     this.parameters = new HashMap<>();
     this.conditions = new ArrayList<>();
@@ -86,6 +86,7 @@ public Template(String etag) {
     if (templateResponse.getVersion() != null) {
       this.version = new Version(templateResponse.getVersion());
     }
+    validateExperimentExposurePercents(this.parameters, this.parameterGroups);
     this.etag = templateResponse.getEtag();
   }
 
@@ -278,4 +279,59 @@ public boolean equals(Object o) {
   public int hashCode() {
     return Objects.hash(etag, parameters, conditions, parameterGroups, version);
   }
+
+  private void validateExperimentExposurePercents(
+      Map<String, Parameter> parameters,
+      Map<String, ParameterGroup> parameterGroups) throws FirebaseRemoteConfigException {
+    Map<String, Double> experimentExposurePercents = new HashMap<>();
+    validateParameters(parameters, experimentExposurePercents);
+    if (parameterGroups != null) {
+      for (ParameterGroup group : parameterGroups.values()) {
+        validateParameters(group.getParameters(), experimentExposurePercents);
+      }
+    }
+  }
+
+  private void validateParameters(
+      Map<String, Parameter> parameters,
+      Map<String, Double> experimentExposurePercents) throws FirebaseRemoteConfigException {
+    if (parameters == null) {
+      return;
+    }
+    for (Map.Entry<String, Parameter> entry : parameters.entrySet()) {
+      Parameter parameter = entry.getValue();
+      String parameterName = entry.getKey();
+      checkExposurePercent(parameter.getDefaultValue(), parameterName, experimentExposurePercents);
+      if (parameter.getConditionalValues() != null) {
+        for (ParameterValue value : parameter.getConditionalValues().values()) {
+          checkExposurePercent(value, parameterName, experimentExposurePercents);
+        }
+      }
+    }
+  }
+
+  private void checkExposurePercent(
+      ParameterValue value,
+      String parameterName,
+      Map<String, Double> experimentExposurePercents) throws FirebaseRemoteConfigException {
+    if (value instanceof ParameterValue.ExperimentValue) {
+      ParameterValue.ExperimentValue experimentValue = (ParameterValue.ExperimentValue) value;
+      Double exposurePercent = experimentValue.getExposurePercent();
+      if (exposurePercent != null) {
+        // Enforce range [0, 100]
+        if (exposurePercent < 0 || exposurePercent > 100) {
+          return;
+        }
+        // Enforce consistency for the same experimentId
+        String experimentId = experimentValue.getExperimentId();
+        if (experimentExposurePercents.containsKey(experimentId)) {
+          if (!Objects.equals(experimentExposurePercents.get(experimentId), exposurePercent)) {
+            return;
+          }
+        } else {
+          experimentExposurePercents.put(experimentId, exposurePercent);
+        }
+      }
+    }
+  }
 }

src/main/java/com/google/firebase/remoteconfig/internal/TemplateResponse.java

@@ -288,6 +288,9 @@ public static final class ExperimentValueResponse {
     @Key("variantValue")
     private List<ExperimentVariantValueResponse> experimentVariantValues;
 
+    @Key("exposurePercent")
+    private Double exposurePercent;
+
     public String getExperimentId() {
       return experimentId;
     }
@@ -296,6 +299,10 @@ public List<ExperimentVariantValueResponse> getExperimentVariantValues() {
       return experimentVariantValues;
     }
 
+    public Double getExposurePercent() {
+      return exposurePercent;
+    }
+
     public ExperimentValueResponse setExperimentId(String experimentId) {
       this.experimentId = experimentId;
       return this;
@@ -306,6 +313,11 @@ public ExperimentValueResponse setExperimentVariantValues(
       this.experimentVariantValues = experimentVariantValues;
       return this;
     }
+
+    public ExperimentValueResponse setExposurePercent(Double exposurePercent) {
+      this.exposurePercent = exposurePercent;
+      return this;
+    }
   }
 
   /**