Those javax -> jakarta packages were not part of the JRE. However, those common interfaces are extremely popular.
True but running anything with an http interface will almost always use the javax.http.servlet package for example.
Just for fun, here is a challenge, find me a java 8 enterprise application which doesn't use at least one of these package:
javax.accessibility
Defines a contract between user-interface components and an assistive technology that provides access to those components.
javax.activation
javax.activity
Contains Activity service related exceptions thrown by the ORB machinery during unmarshalling.
javax.annotation
javax.annotation.processing
Facilities for declaring annotation processors and for allowing annotation processors to communicate with an annotation processing tool environment.
javax.crypto
Provides the classes and interfaces for cryptographic operations.
javax.crypto.interfaces
Provides interfaces for Diffie-Hellman keys as defined in RSA Laboratories' PKCS #3.
javax.crypto.spec
Provides classes and interfaces for key specifications and algorithm parameter specifications.
javax.imageio
The main package of the Java Image I/O API.
javax.imageio.event
A package of the Java Image I/O API dealing with synchronous notification of events during the reading and writing of images.
javax.imageio.metadata
A package of the Java Image I/O API dealing with reading and writing metadata.
javax.imageio.plugins.bmp
Package containing the public classes used by the built-in BMP plug-in.
javax.imageio.plugins.jpeg
Classes supporting the built-in JPEG plug-in.
javax.imageio.spi
A package of the Java Image I/O API containing the plug-in interfaces for readers, writers, transcoders, and streams, and a runtime registry.
javax.imageio.stream
A package of the Java Image I/O API dealing with low-level I/O from files and streams.
javax.jws
javax.jws.soap
javax.lang.model
Classes and hierarchies of packages used to model the Java programming language.
javax.lang.model.element
Interfaces used to model elements of the Java programming language.
javax.lang.model.type
Interfaces used to model Java programming language types.
javax.lang.model.util
Utilities to assist in the processing of program elements and types.
javax.management
Provides the core classes for the Java Management Extensions.
javax.management.loading
Provides the classes which implement advanced dynamic loading.
javax.management.modelmbean
Provides the definition of the ModelMBean classes.
javax.management.monitor
Provides the definition of the monitor classes.
javax.management.openmbean
Provides the open data types and Open MBean descriptor classes.
javax.management.relation
Provides the definition of the Relation Service.
javax.management.remote
Interfaces for remote access to JMX MBean servers.
javax.management.remote.rmi
The RMI connector is a connector for the JMX Remote API that uses RMI to transmit client requests to a remote MBean server.
javax.management.timer
Provides the definition of the Timer MBean.
javax.naming
Provides the classes and interfaces for accessing naming services.
javax.naming.directory
Extends the javax.naming package to provide functionality for accessing directory services.
javax.naming.event
Provides support for event notification when accessing naming and directory services.
javax.naming.ldap
Provides support for LDAPv3 extended operations and controls.
javax.naming.spi
javax.net
Provides classes for networking applications.
javax.net.ssl
Provides classes for the secure socket package.
javax.print
Provides the principal classes and interfaces for the JavaTM Print Service API.
javax.print.attribute
Provides classes and interfaces that describe the types of JavaTM Print Service attributes and how they can be collected into attribute sets.
javax.print.attribute.standard
Package javax.print.attribute.standard contains classes for specific printing attributes.
javax.print.event
Package javax.print.event contains event classes and listener interfaces.
javax.rmi
Contains user APIs for RMI-IIOP.
javax.rmi.CORBA
Contains portability APIs for RMI-IIOP.
javax.rmi.ssl
Provides implementations of RMIClientSocketFactory and RMIServerSocketFactory over the Secure Sockets Layer (SSL) or Transport Layer Security (TLS) protocols.
javax.script
The scripting API consists of interfaces and classes that define Java TM Scripting Engines and provides a framework for their use in Java applications.
javax.security.auth
This package provides a framework for authentication and authorization.
javax.security.auth.callback
This package provides the classes necessary for services to interact with applications in order to retrieve information (authentication data including usernames or passwords, for example) or to display information (error and warning messages, for example).
javax.security.auth.kerberos
This package contains utility classes related to the Kerberos network authentication protocol.
javax.security.auth.login
This package provides a pluggable authentication framework.
javax.security.auth.spi
This package provides the interface to be used for implementing pluggable authentication modules.
javax.security.auth.x500
This package contains the classes that should be used to store X500 Principal and X500 Private Credentials in a Subject.
javax.security.cert
Provides classes for public key certificates.
javax.security.sasl
Contains class and interfaces for supporting SASL.
javax.sound.midi
Provides interfaces and classes for I/O, sequencing, and synthesis of MIDI (Musical Instrument Digital Interface) data.
javax.sound.midi.spi
Supplies interfaces for service providers to implement when offering new MIDI devices, MIDI file readers and writers, or sound bank readers.
javax.sound.sampled
Provides interfaces and classes for capture, processing, and playback of sampled audio data.
javax.sound.sampled.spi
Supplies abstract classes for service providers to subclass when offering new audio devices, sound file readers and writers, or audio format converters.
javax.sql
Provides the API for server side data source access and processing from the JavaTM programming language.
javax.sql.rowset
Standard interfaces and base classes for JDBC RowSet implementations.
javax.sql.rowset.serial
Provides utility classes to allow serializable mappings between SQL types and data types in the Java programming language.
javax.sql.rowset.spi
The standard classes and interfaces that a third party vendor has to use in its implementation of a synchronization provider.
javax.swing
Provides a set of "lightweight" (all-Java language) components that, to the maximum degree possible, work the same on all platforms.
javax.swing.border
Provides classes and interface for drawing specialized borders around a Swing component.
javax.swing.colorchooser
Contains classes and interfaces used by the JColorChooser component.
javax.swing.event
Provides for events fired by Swing components.
javax.swing.filechooser
Contains classes and interfaces used by the JFileChooser component.
javax.swing.plaf
Provides one interface and many abstract classes that Swing uses to provide its pluggable look-and-feel capabilities.
javax.swing.plaf.basic
Provides user interface objects built according to the Basic look and feel.
javax.swing.plaf.metal
Provides user interface objects built according to the Java look and feel (once codenamed Metal), which is the default look and feel.
javax.swing.plaf.multi
Provides user interface objects that combine two or more look and feels.
javax.swing.plaf.nimbus
Provides user interface objects built according to the cross-platform Nimbus look and feel.
javax.swing.plaf.synth
Synth is a skinnable look and feel in which all painting is delegated.
javax.swing.table
Provides classes and interfaces for dealing with javax.swing.JTable.
javax.swing.text
Provides classes and interfaces that deal with editable and noneditable text components.
javax.swing.text.html
Provides the class HTMLEditorKit and supporting classes for creating HTML text editors.
javax.swing.text.html.parser
Provides the default HTML parser, along with support classes.
javax.swing.text.rtf
Provides a class (RTFEditorKit) for creating Rich-Text-Format text editors.
javax.swing.tree
Provides classes and interfaces for dealing with javax.swing.JTree.
javax.swing.undo
Allows developers to provide support for undo/redo in applications such as text editors.
javax.tools
Provides interfaces for tools which can be invoked from a program, for example, compilers.
javax.transaction
Contains three exceptions thrown by the ORB machinery during unmarshalling.
javax.transaction.xa
Provides the API that defines the contract between the transaction manager and the resource manager, which allows the transaction manager to enlist and delist resource objects (supplied by the resource manager driver) in JTA transactions.
javax.xml
javax.xml.bind
Provides a runtime binding framework for client applications including unmarshalling, marshalling, and validation capabilities.
javax.xml.bind.annotation
Defines annotations for customizing Java program elements to XML Schema mapping.
javax.xml.bind.annotation.adapters
XmlAdapter and its spec-defined sub-classes to allow arbitrary Java classes to be used with JAXB.
javax.xml.bind.attachment
This package is implemented by a MIME-based package processor that enables the interpretation and creation of optimized binary data within an MIME-based package format.
javax.xml.bind.helpers
JAXB Provider Use Only: Provides partial default implementations for some of the javax.xml.bind interfaces.
javax.xml.bind.util
Useful client utility classes.
javax.xml.crypto
Common classes for XML cryptography.
javax.xml.crypto.dom
DOM-specific classes for the javax.xml.crypto package.
javax.xml.crypto.dsig
Classes for generating and validating XML digital signatures.
javax.xml.crypto.dsig.dom
DOM-specific classes for the javax.xml.crypto.dsig package.
javax.xml.crypto.dsig.keyinfo
Classes for parsing and processing KeyInfo elements and structures.
javax.xml.crypto.dsig.spec
Parameter classes for XML digital signatures.
javax.xml.datatype
XML/Java Type Mappings.
javax.xml.namespace
XML Namespace processing.
javax.xml.parsers
Provides classes allowing the processing of XML documents.
javax.xml.soap
Provides the API for creating and building SOAP messages.
javax.xml.stream
javax.xml.stream.events
javax.xml.stream.util
javax.xml.transform
This package defines the generic APIs for processing transformation instructions, and performing a transformation from source to result.
javax.xml.transform.dom
This package implements DOM-specific transformation APIs.
javax.xml.transform.sax
This package implements SAX2-specific transformation APIs.
javax.xml.transform.stax
Provides for StAX-specific transformation APIs.
javax.xml.transform.stream
This package implements stream- and URI- specific transformation APIs.
javax.xml.validation
This package provides an API for validation of XML documents.
javax.xml.ws
This package contains the core JAX-WS APIs.
javax.xml.ws.handler
This package defines APIs for message handlers.
javax.xml.ws.handler.soap
This package defines APIs for SOAP message handlers.
javax.xml.ws.http
This package defines APIs specific to the HTTP binding.
javax.xml.ws.soap
This package defines APIs specific to the SOAP binding.
javax.xml.ws.spi
This package defines SPIs for JAX-WS.
javax.xml.ws.spi.http
Provides HTTP SPI that is used for portable deployment of JAX-WS web services in containers(for e.g.
javax.xml.ws.wsaddressing
This package defines APIs related to WS-Addressing.
javax.xml.xpath
This package provides an object-model neutral API for the evaluation of XPath expressions and access to the evaluation environment.