Support pageStart in x-pagination extension

Add support for the pageStart field in the x-pagination OpenAPI extension
to allow APIs that use 1-based page numbering (like Case Management) to
work correctly with pagination helpers.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: amaskara-dd

.generator/src/generator/templates/Api.j2

@@ -148,7 +148,7 @@ public class {{ name }} {
   String valueGetterPath = "";
   String valueSetterPath = "{%- if getters|length > 1 %}{{ ".".join(getters[:getters|length-1]) }}.{%- endif %}{{ setters[getters|length-1] }}";
   Boolean valueSetterParamOptional = {{ optional|lower }};
-  parameters.{% if getters|length > 1 %}{{ ".".join(getters[:getters|length-1]) }}.{%- endif %}{{ setters[getters|length-1] }}({{ 0|format_value(schema=paramSchema['schema']) }});
+  parameters.{% if getters|length > 1 %}{{ ".".join(getters[:getters|length-1]) }}.{%- endif %}{{ setters[getters|length-1] }}({{ (pagination.pageStart | default(0))|format_value(schema=paramSchema['schema']) }});
   {%- endif %}
 
 {#- Limit param field #}
@@ -205,7 +205,7 @@ public class {{ name }} {
   args.put("optionalParams", parameters);
   {%- endif  %}
 
-  PaginationIterable iterator = new PaginationIterable(this, "{{ operationId }}", resultsPath, valueGetterPath, valueSetterPath, valueSetterParamOptional, {% if pagination.pageParam %}false{% else %}true{% endif %}, limit, args);
+  PaginationIterable iterator = new PaginationIterable(this, "{{ operationId }}", resultsPath, valueGetterPath, valueSetterPath, valueSetterParamOptional, {% if pagination.pageParam %}false{% else %}true{% endif %}, limit, args, {{ pagination.pageStart | default(0) }});
 
   return iterator;
 {%- endmacro %}

.generator/src/generator/templates/PaginationIterable.j2

@@ -14,6 +14,7 @@ public class PaginationIterable<T> implements Iterable<T> {
   Boolean offsetPageIncrement;
   Object limit;
   LinkedHashMap<String, Object> args;
+  int pageStart;
 
   public PaginationIterable(
       Object requestClass,
@@ -24,7 +25,8 @@ public class PaginationIterable<T> implements Iterable<T> {
       Boolean valueSetterParamOptional,
       Boolean offsetPageIncrement,
       Object limit,
-      LinkedHashMap<String, Object> args) {
+      LinkedHashMap<String, Object> args,
+      int pageStart) {
 
     this.requestClass = requestClass;
     this.requestName = requestName;
@@ -41,6 +43,7 @@ public class PaginationIterable<T> implements Iterable<T> {
     this.offsetPageIncrement = offsetPageIncrement;
     this.limit = limit;
     this.args = args;
+    this.pageStart = pageStart;
   }
 
   @Override

.generator/src/generator/templates/PaginationIterator.j2

@@ -80,13 +80,13 @@ public class PaginationIterator<T> implements Iterator<T> {
         value = value.getClass().getMethod(path).invoke(value);
       }
     } else {
-      // fallback to pageOffset = totalCount;
+      // fallback to pageOffset = pageStart + totalCount;
       // We cast the type based on the setterMethod parameter type
       String pType = setterMethod.getParameterTypes()[0].getSimpleName();
       if ("Long".equals(pType)) {
-        value = (long) this.totalCount;
+        value = (long) (this.iterable.pageStart + this.totalCount);
       } else {
-        value = this.totalCount;
+        value = this.iterable.pageStart + this.totalCount;
       }
     }