diff --git a/src/main/java/io/weaviate/client6/v1/api/Config.java b/src/main/java/io/weaviate/client6/v1/api/Config.java
index 50abb2f02..f1da7a136 100644
--- a/src/main/java/io/weaviate/client6/v1/api/Config.java
+++ b/src/main/java/io/weaviate/client6/v1/api/Config.java
@@ -23,7 +23,7 @@ public static Config of(Function<Custom, ObjectBuilder<Config>> fn) {
     return fn.apply(new Custom()).build();
   }
 
-  public Config(Builder<?> builder) {
+  private Config(Builder<?> builder) {
     this(
         builder.scheme,
         builder.httpHost,
@@ -42,7 +42,7 @@ public GrpcChannelOptions grpcTransportOptions() {
     return new GrpcChannelOptions(scheme, grpcHost, grpcPort, headers, tokenProvider);
   }
 
-  abstract static class Builder<SELF extends Builder<SELF>> implements ObjectBuilder<Config> {
+  private abstract static class Builder<SELF extends Builder<SELF>> implements ObjectBuilder<Config> {
     protected String scheme;
 
     protected String httpHost;
@@ -158,8 +158,8 @@ public static class Custom extends Builder<Custom> {
      * <strong>443</strong> for HTTPS connection and <strong>80</strong> for HTTP.
      */
     public Custom scheme(String scheme) {
-      httpPort(scheme == "https" ? 443 : 80);
-      grpcPort(scheme == "https" ? 443 : 80);
+      httpPort("https".equals(scheme) ? 443 : 80);
+      grpcPort("https".equals(scheme) ? 443 : 80);
       return super.scheme(scheme);
     }
 
@@ -169,7 +169,7 @@ public Custom httpHost(String httpHost) {
     }
 
     public Custom httpPort(int port) {
-      this.grpcPort = port;
+      this.httpPort = port;
       return this;
     }