code: public SpekeKeyProvider withSystemIds(String... systemIds) {
          if (this.systemIds == null) {
              setSystemIds(new java.util.ArrayList<String>(systemIds.length));
          }
          for (String ele : systemIds) {
              this.systemIds.add(ele);
          }
          return this;
      }
docs: Relates to SPEKE implementation. DRM system identifiers. DASH output groups support a max of two system ids.
  Other group types support one system id.
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setSystemIds(java.util.Collection)} or {@link #withSystemIds(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param systemIds
  Relates to SPEKE implementation. DRM system identifiers. DASH output groups support a max of two system
  ids. Other group types support one system id.
  @return Returns a reference to this object so that method calls can be chained together.