chore: regenerate content client (googleapis#26567)

Generated in GitHub action: https://togithub.com/googleapis/googleapis/google-api-java-client-services/actions/workflows/codegen.yaml

Author: yoshi-code-bot

clients/google-api-services-content/v2.1/2.0.0/README.md

@@ -22,7 +22,7 @@ Add the following lines to your `pom.xml` file:
     <dependency>
       <groupId>com.google.apis</groupId>
       <artifactId>google-api-services-content</artifactId>
-      <version>v2.1-rev20250301-2.0.0</version>
+      <version>v2.1-rev20250408-2.0.0</version>
     </dependency>
   </dependencies>
 </project>
@@ -35,7 +35,7 @@ repositories {
   mavenCentral()
 }
 dependencies {
-  implementation 'com.google.apis:google-api-services-content:v2.1-rev20250301-2.0.0'
+  implementation 'com.google.apis:google-api-services-content:v2.1-rev20250408-2.0.0'
 }
 ```
 

clients/google-api-services-content/v2.1/2.0.0/com/google/api/services/content/model/Product.java

@@ -19,7 +19,9 @@
 /**
  * Required product attributes are primarily defined by the product data specification. See the
  * Product Data Specification Help Center article for information. Product data. After inserting,
- * updating, or deleting a product, it may take several minutes before changes take effect.
+ * updating, or deleting a product, it may take several minutes before changes take effect. The
+ * following reference documentation lists the field names in the **camelCase** casing style while
+ * the Products Data Specification lists the names in the **snake_case** casing style.
  *
  * <p> This is the Java data model class that specifies how to parse/serialize into the JSON that is
  * transmitted over HTTP when working with the Content API for Shopping. For a detailed explanation

clients/google-api-services-content/v2.1/2.0.0/pom.xml

@@ -8,8 +8,8 @@
 
   <groupId>com.google.apis</groupId>
   <artifactId>google-api-services-content</artifactId>
-  <version>v2.1-rev20250301-2.0.0</version>
-  <name>Content API for Shopping v2.1-rev20250301-2.0.0</name>
+  <version>v2.1-rev20250408-2.0.0</version>
+  <name>Content API for Shopping v2.1-rev20250408-2.0.0</name>
   <packaging>jar</packaging>
 
   <inceptionYear>2011</inceptionYear>

clients/google-api-services-content/v2.1/README.md

@@ -22,7 +22,7 @@ Add the following lines to your `pom.xml` file:
     <dependency>
       <groupId>com.google.apis</groupId>
       <artifactId>google-api-services-content</artifactId>
-      <version>v2.1-rev20250301-2.0.0</version>
+      <version>v2.1-rev20250408-2.0.0</version>
     </dependency>
   </dependencies>
 </project>
@@ -35,7 +35,7 @@ repositories {
   mavenCentral()
 }
 dependencies {
-  implementation 'com.google.apis:google-api-services-content:v2.1-rev20250301-2.0.0'
+  implementation 'com.google.apis:google-api-services-content:v2.1-rev20250408-2.0.0'
 }
 ```