[Feature] Remove proxy settings from databricks config and use common…

…s http client builder for connection manager (#337)

## Changes
<!-- Summary of your changes that are easy to understand -->
Add the ability to provide non proxy hosts via databricks config as well

## Tests
<!-- How is this tested? -->
Local testing

databricks-sdk-java/src/main/java/com/databricks/sdk/core/DatabricksConfig.java

@@ -132,24 +132,6 @@ public class DatabricksConfig {
   @ConfigAttribute(env = "DATABRICKS_RATE_LIMIT")
   private Integer rateLimit;
 
-  @ConfigAttribute(env = "PROXY_HOST")
-  private String proxyHost;
-
-  @ConfigAttribute(env = "PROXY_PORT")
-  private Integer proxyPort;
-
-  @ConfigAttribute(env = "PROXY_USERNAME")
-  private String proxyUsername;
-
-  @ConfigAttribute(env = "PROXY_PASSWORD")
-  private String proxyPassword;
-
-  @ConfigAttribute(env = "PROXY_AUTH_TYPE")
-  private ProxyConfig.ProxyAuthType proxyAuthType;
-
-  @ConfigAttribute(env = "USE_SYSTEM_PROPERTIES_HTTP")
-  private Boolean useSystemPropertiesHttp;
-
   private volatile boolean resolved;
   private HeaderFactory headerFactory;
 
@@ -530,60 +512,6 @@ public DatabricksConfig setHttpClient(HttpClient httpClient) {
     return this;
   }
 
-  public String getProxyHost() {
-    return proxyHost;
-  }
-
-  public DatabricksConfig setProxyHost(String proxyHost) {
-    this.proxyHost = proxyHost;
-    return this;
-  }
-
-  public Integer getProxyPort() {
-    return proxyPort;
-  }
-
-  public DatabricksConfig setProxyPort(Integer proxyPort) {
-    this.proxyPort = proxyPort;
-    return this;
-  }
-
-  public String getProxyUsername() {
-    return proxyUsername;
-  }
-
-  public DatabricksConfig setProxyUsername(String proxyUsername) {
-    this.proxyUsername = proxyUsername;
-    return this;
-  }
-
-  public String getProxyPassword() {
-    return proxyPassword;
-  }
-
-  public DatabricksConfig setProxyPassword(String proxyPassword) {
-    this.proxyPassword = proxyPassword;
-    return this;
-  }
-
-  public ProxyConfig.ProxyAuthType getProxyAuthType() {
-    return proxyAuthType;
-  }
-
-  public DatabricksConfig setProxyAuthType(ProxyConfig.ProxyAuthType proxyAuthType) {
-    this.proxyAuthType = proxyAuthType;
-    return this;
-  }
-
-  public Boolean getUseSystemPropertiesHttp() {
-    return useSystemPropertiesHttp;
-  }
-
-  public DatabricksConfig setUseSystemPropertiesHttp(Boolean useSystemPropertiesHttp) {
-    this.useSystemPropertiesHttp = useSystemPropertiesHttp;
-    return this;
-  }
-
   public boolean isAzure() {
     if (azureWorkspaceResourceId != null) {
       return true;

databricks-sdk-java/src/main/java/com/databricks/sdk/core/ProxyConfig.java

@@ -25,15 +25,6 @@ public enum ProxyAuthType {
 
   public ProxyConfig() {}
 
-  public ProxyConfig(DatabricksConfig config) {
-    this.host = config.getProxyHost();
-    this.port = config.getProxyPort();
-    this.username = config.getProxyUsername();
-    this.password = config.getProxyPassword();
-    this.proxyAuthType = config.getProxyAuthType();
-    this.useSystemProperties = config.getUseSystemPropertiesHttp();
-  }
-
   public String getHost() {
     return host;
   }

databricks-sdk-java/src/main/java/com/databricks/sdk/core/commons/CommonsHttpClient.java

@@ -46,6 +46,7 @@ public static class Builder {
     private Integer timeoutSeconds;
     private ProxyConfig proxyConfig;
     private SSLConnectionSocketFactory sslSocketFactory;
+    private PoolingHttpClientConnectionManager connectionManager;
 
     /**
      * @param databricksConfig The DatabricksConfig to use for the HttpClient. If the
@@ -86,19 +87,28 @@ public Builder withSslSocketFactory(SSLConnectionSocketFactory sslSocketFactory)
       return this;
     }
 
+    /**
+     * @param connectionManager the PoolingHttpClientConnectionManager to use for the HttpClient.
+     * @return This builder.
+     */
+    public Builder withConnectionManager(PoolingHttpClientConnectionManager connectionManager) {
+      this.connectionManager = connectionManager;
+      return this;
+    }
+
     /** Builds a new instance of CommonsHttpClient with the configured parameters. */
     public CommonsHttpClient build() {
       return new CommonsHttpClient(this);
     }
   }
 
   private static final Logger LOG = LoggerFactory.getLogger(CommonsHttpClient.class);
-  private final PoolingHttpClientConnectionManager connectionManager =
-      new PoolingHttpClientConnectionManager();
   private final CloseableHttpClient hc;
   private int timeout;
 
   private CommonsHttpClient(Builder builder) {
+    HttpClientBuilder httpClientBuilder =
+        HttpClientBuilder.create().setDefaultRequestConfig(makeRequestConfig());
     int timeoutSeconds = 300;
     if (builder.databricksConfig != null
         && builder.databricksConfig.getHttpTimeoutSeconds() != null) {
@@ -108,45 +118,23 @@ private CommonsHttpClient(Builder builder) {
       timeoutSeconds = builder.timeoutSeconds;
     }
     timeout = timeoutSeconds * 1000;
-    connectionManager.setMaxTotal(100);
-    HttpClientBuilder httpClientBuilder =
-        HttpClientBuilder.create()
-            .setConnectionManager(connectionManager)
-            .setDefaultRequestConfig(makeRequestConfig());
     if (builder.proxyConfig != null) {
       ProxyUtils.setupProxy(builder.proxyConfig, httpClientBuilder);
     }
     if (builder.sslSocketFactory != null) {
       httpClientBuilder.setSSLSocketFactory(builder.sslSocketFactory);
     }
+    if (builder.connectionManager != null) {
+      httpClientBuilder.setConnectionManager(builder.connectionManager);
+    } else {
+      PoolingHttpClientConnectionManager connectionManager =
+          new PoolingHttpClientConnectionManager();
+      connectionManager.setMaxTotal(100);
+      httpClientBuilder.setConnectionManager(connectionManager);
+    }
     hc = httpClientBuilder.build();
   }
 
-  // These constructors have been deprecate in favour of a builder pattern.
-  // They will be removed in a future release.
-  @Deprecated
-  public CommonsHttpClient(int timeoutSeconds) {
-    timeout = timeoutSeconds * 1000;
-    connectionManager.setMaxTotal(100);
-    hc = makeClosableHttpClient();
-  }
-
-  @Deprecated
-  public CommonsHttpClient(DatabricksConfig databricksConfig) {
-    this(
-        databricksConfig.getHttpTimeoutSeconds() == null
-            ? 300
-            : databricksConfig.getHttpTimeoutSeconds(),
-        new ProxyConfig(databricksConfig));
-  }
-
-  @Deprecated
-  public CommonsHttpClient(int timeoutSeconds, ProxyConfig proxyConfig) {
-    timeout = timeoutSeconds * 1000;
-    connectionManager.setMaxTotal(100);
-    hc = makeClosableHttpClient(proxyConfig);
-  }
-
   private RequestConfig makeRequestConfig() {
     return RequestConfig.custom()
         .setConnectionRequestTimeout(timeout)
@@ -155,24 +143,6 @@ private RequestConfig makeRequestConfig() {
         .build();
   }
 
-  @Deprecated
-  private CloseableHttpClient makeClosableHttpClient() {
-    return HttpClientBuilder.create()
-        .setConnectionManager(connectionManager)
-        .setDefaultRequestConfig(makeRequestConfig())
-        .build();
-  }
-
-  @Deprecated
-  private CloseableHttpClient makeClosableHttpClient(ProxyConfig proxyConfig) {
-    HttpClientBuilder builder =
-        HttpClientBuilder.create()
-            .setConnectionManager(connectionManager)
-            .setDefaultRequestConfig(makeRequestConfig());
-    ProxyUtils.setupProxy(proxyConfig, builder);
-    return builder.build();
-  }
-
   @Override
   public Response execute(Request in) throws IOException {
     HttpUriRequest request = transformRequest(in);

databricks-sdk-java/src/test/java/com/databricks/sdk/core/DatabricksConfigTest.java

@@ -129,7 +129,7 @@ public void testDiscoveryEndpoint() throws IOException {
           new DatabricksConfig()
               .setHost(server.getUrl())
               .setDiscoveryUrl(discoveryUrl)
-              .setHttpClient(new CommonsHttpClient(30))
+              .setHttpClient(new CommonsHttpClient.Builder().withTimeoutSeconds(30).build())
               .getOidcEndpoints();
 
       assertEquals(